GSEB Class 10 Science Solutions Chapter 8 How do Organisms Reproduce

 

Question 1. What is the importance of DNA copying in reproduction?
Answer: DNA replication is a key aspect of reproduction, allowing organisms to transfer their traits to their progeny. It helps keep the traits consistent across various generations of a species. It also creates differences that are helpful for species to survive over a long period.
In simple words: DNA copying helps organisms give their traits to their babies. It keeps the traits the same over many generations and also creates small changes that help the species live longer.

Exam Tip: Explain how DNA copying ensures both heredity and variation, which are crucial for species survival.

 

Question 2. Why is variation beneficial to the species but not necessary for the individual?
Answer: The build-up of differences after many generations leads to new sets of traits needed for survival. Since these changes only show effects after numerous generations, they are not vital for a single individual.
In simple words: Small changes gathering over time create new features that help a species survive. But these changes take many generations to become clear, so they aren't needed for one individual to live.

Exam Tip: Distinguish between the benefits of variation for the collective species (long-term survival, evolution) and its less direct impact on a single organism's immediate survival.

 

Question 3. How does binary fission differ from multiple fission?
Answer:
Binary Fission: In this, an organism splits into two separate individuals. Mitotic cell division happens, producing two identical individuals or daughter cells. An example is Amoeba.
Multiple Fission: Here, mitotic cell division occurs. The nucleus repeatedly divides to create many identical and similar-sized individuals. An example is Plasmodium.
In simple words: Binary fission means one organism splits into two new ones, like Amoeba. Multiple fission means one organism splits into many new ones, like Plasmodium.

Exam Tip: Clearly define both processes and provide a distinct example for each to show your understanding of the differences.

 

Question 4. How will an organism be benefited if it reproduces through spores?
Answer: When conditions are harsh, spores have a tough outer layer. This helps an organism get through difficult situations. Spores offer a way to overcome unfavorable periods.
In simple words: Spores have a strong covering that protects the organism when conditions are bad, helping it survive until things get better.

Exam Tip: Focus on the protective nature of the spore's coating and its role in survival during harsh environmental conditions.

 

Question 5. Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration?
Answer: More complex organisms cannot produce new individuals through regeneration for these reasons:
* Their overall body structure is very intricate.
* They have particular organs that perform specific duties.
* There is a division of tasks within the bodies of complex organisms.
* A special case is the lizard, which can regrow its tail.
In simple words: Complex creatures can't regrow whole new bodies because their bodies are too complicated, have special parts for different jobs, and have a system where different parts do different work. Lizards are an exception as they can regrow their tail.

Exam Tip: Emphasize the increased specialization and complexity of tissues and organs in higher organisms, which makes widespread regeneration impossible.

 

Question 6. Why is vegetative propagation practised for growing some types of plants?
Answer: Vegetative propagation is the method where some plants can reproduce without seeds using their vegetative parts such as roots, stems, and leaves. This method offers several benefits. Plants grown this way can produce flowers and fruits sooner than those started from seeds. It also helps propagate plants that cannot produce seeds, like bananas, oranges, roses, and jasmine. All new plants created using this technique are genetically identical to the original plant.
In simple words: Vegetative propagation is used because it helps plants grow faster and produce fruits and flowers sooner. It's also good for plants that don't make seeds, and all new plants are exact copies of the parent.

Exam Tip: List the key advantages like faster growth, early fruiting, propagation of seedless plants, and genetic uniformity when explaining why this method is used.

 

Question 7. Why is DNA copying an essential part of the process of reproduction? (AI 2009)
Answer: DNA copying is crucial because the information held in DNA is utilized to create proteins. The production of various proteins results in a changed body structure. So, reproduction, at its simplest form, means making duplicates of the fundamental plans for body structure.
In simple words: DNA copying is vital for reproduction because DNA holds the instructions for making proteins, which determine body design. Creating new copies ensures these instructions are passed on to new organisms.

Exam Tip: Explain that DNA contains genetic information for protein synthesis, which dictates body design, and copying it ensures the faithful transmission of these blueprints to the next generation.

 

Question 8. How is the process of pollination different from fertilization?
Answer: Pollination is the movement of pollen grains from a stamen's anther to a carpel's stigma. This transfer happens through agents like insects, birds, wind, or water. Fertilization is described as the joining of a male gamete (sperm) with a female gamete (from the ovary) to create a zygote through sexual reproduction.
In simple words: Pollination is just moving pollen to the stigma, often by wind or insects. Fertilization is when the male and female reproductive cells actually join together to create a new organism.

Exam Tip: Clearly differentiate between pollination as a transfer mechanism and fertilization as the actual fusion of gametes, noting the agents involved in the former.

 

Question 9. What is the role of seminal vesicles and prostate gland?
Answer: Seminal vesicles are two thin-walled, muscular, and long sacs that release a fluid to nourish sperm. Prostate glands also create a fluid, which is released into the urethra along with the seminal vesicle's secretion. This fluid changes the vaginal pH, helping sperm move easily within the vagina.
In simple words: Seminal vesicles give food to sperm, and the prostate gland makes a fluid that helps sperm move easily by changing the environment.

Exam Tip: Mention that both glands produce fluids, specifying the nourishing role of seminal vesicles and the pH-modifying/lubricating role of the prostate gland for sperm motility.

 

Question 10. What are the changes seen in girls at the time of puberty?
Answer: During puberty, girls experience an increase in breast size, and the skin around the nipples becomes darker. Additionally, menstruation typically starts around this period.
In simple words: At puberty, girls' breasts grow, nipples darken, and they start their monthly period (menstruation).

Exam Tip: Focus on the primary and secondary sexual characteristics that develop during female puberty, such as breast development and the onset of menstruation.

 

Question 11. How does the embryo get nourished inside the mother's body?
Answer: The embryo develops inside the mother's womb and receives sustenance from her blood via the placenta. The placenta has villi, which connect the embryo to the mother's blood. These villi offer a large area for glucose and oxygen to transfer from the mother to the developing embryo.
In simple words: The embryo gets food and oxygen from the mother's blood through a special organ called the placenta. The placenta acts like a bridge, letting important nutrients pass to the baby.

Exam Tip: Explain the role of the placenta as the vital link for nutrient and oxygen exchange between mother and embryo, highlighting the villi for increased surface area.

 

Question 12. If a woman is using copper-T, will it help in protecting her from sexually transmitted diseases?
Answer: No, a copper-T will not keep a woman safe from sexually transmitted infections, because direct fluid contact still happens in the vagina.
In simple words: No, a copper-T only stops pregnancy. It does not protect against STDs because fluids can still exchange during contact.

Exam Tip: Clarify that contraception methods like Copper-T primarily prevent pregnancy and do not offer protection against STIs, which require barrier methods like condoms.

 

Activity 8.1
Answer:
Aim: To show how asexual reproduction occurs through budding.
Materials needed: Sugar, water, a test tube, yeast granules, cotton, a slide, and a coverslip.
Procedure: First, dissolve about 10 grams of sugar in 100 ml of water. Then, pour 20 ml of this mixture into a test tube and add a small amount of yeast granules. Place a cotton stopper on the test tube's opening and store it in a warm spot. After one or two hours, place a small drop of the yeast culture from the test tube onto a slide and cover it with a coverslip.
Observation: You will notice that the yeast undergoes asexual reproduction by budding.
The diagram illustrates the process of budding in yeast cells. It shows a series of stages: a parent yeast cell with a nucleus and vacuole; a small bud formation emerging from the parent cell; the nucleus from the parent cell moving into the developing bud; the bud continuing to grow, eventually forming a bud with its own nucleus; and finally, the bud detaching from the parent cell, leaving a birth scar on the parent and a bud scar on the new daughter yeast cell. This shows how a new, smaller yeast cell grows directly from the parent cell.
In simple words: This activity shows how yeast makes new cells by budding. We mix yeast with sugar water, let it sit, then look under a microscope. We see small new yeast cells growing out of the bigger ones.

Exam Tip: For activity-based questions, accurately describe the setup, procedure, and observations, clearly linking the findings to the biological concept being demonstrated.

 

Activity 8.3
Answer:
(Bread Mould):
Procedure: Wet a slice of bread, and keep it in a cool, moist and dark place. Observe the surface of the slice with a magnifying glass. Record your observations for a week.
Observation: Fungi, known as bread mould, will grow on the bread; it starts white and later changes to brown or black as it matures.
The diagram shows a bread mould structure. It consists of root-like hyphae embedded in the bread, with upright stalks (sporangiophores) that bear rounded structures at their tips called sporangia. These sporangia contain spores, which are released for reproduction.
(Amoeba):
Procedure: Observe a permanent slide of Amoeba under a microscope. Similarly, observe another permanent slide of Amoeba showing binary fission. Compare the observations of both the slides.
Observation: The slide of Amoeba displays a single Amoeba, and the one undergoing binary fission appears as a larger Amoeba with a noticeable narrowing in its middle.
The diagram illustrates binary fission in Amoeba. It starts with a single amoeba cell. Then, the cell elongates, and its nucleus begins to divide. A constriction forms in the middle of the cell, which deepens, eventually dividing the cytoplasm and separating the single amoeba into two smaller, identical daughter amoebae.
In simple words: This activity shows how mould grows on bread and how Amoeba divides. On bread, mould grows from white to black. For Amoeba, we see a single cell, and then a larger one splitting into two.

Exam Tip: When describing experiments, clearly outline the materials, steps, and expected outcomes, focusing on the biological processes observed.

 

Activity 8.4
Answer: Collect water from a lake or pond that looks dark green and has filamentous structures. Place one or two of these filaments on a slide. Add a drop of glycerine to them and then cover with a coverslip. Examine the slide under a microscope.
In simple words: Take green, stringy water from a pond, put some strings on a slide, add a drop of oil, cover it, and look at it under a microscope.

Exam Tip: When describing a simple experiment, clearly state the materials, setup, and key steps for observation under a microscope.

 

Activity 8.5
Answer:
Procedure: Obtain a potato and examine its surface, noting the indentations (known as 'eyes'). Cut the potato into small parts, ensuring some pieces include a notch or bud while others do not. Spread some cotton on a tray and moisten it. Place the potato pieces on this damp cotton. Keep track of where the bud-containing pieces are located. Watch for any changes in these potato pieces over the following days, making sure the cotton remains moist.
Observation: Potato pieces with notches or buds exhibit the development of new plants, while other potato pieces without these features do not show similar growth.
The diagram shows a potato with small buds growing from its 'eyes' or notches. It illustrates that these buds can develop into new shoots and roots, especially when kept on wet cotton, demonstrating vegetative propagation in potatoes.
In simple words: This activity shows how potatoes grow from their 'eyes'. We put potato pieces (some with eyes, some without) on wet cotton. Only the pieces with 'eyes' will start to grow new plants.

Exam Tip: For practical activities, clearly state the steps, expected observations, and the biological principle demonstrated (e.g., vegetative propagation from buds).

 

Activity 8.6
Answer:
Procedure: Choose a money plant. Cut several pieces, ensuring some have at least one leaf. Also, cut some other sections from between two leaves. Submerge one end of all these pieces in water and monitor them over the next few days. Note which pieces develop and produce new leaves.
Observation: The money plant stems with leaves demonstrated growth, whereas the other segments taken from between leaves did not show any development.
In simple words: This activity shows how money plants grow from cuttings. We take pieces of the plant, some with leaves, some without, and put them in water. Only the pieces with leaves will grow new roots and leaves.

Exam Tip: For activity-based questions, accurately describe the setup, procedure, and observations, clearly linking the findings to the biological concept being demonstrated.

 

Activity 8.7
Answer:
Procedure: Soak some Bengal gram (chana) seeds overnight. Remove the extra water and cover the seeds with a damp cloth, leaving them for a day. Ensure the seeds stay moist. Carefully open the seeds and examine their various components, identifying each part.
Observation: The seed has two cotyledons (making it a dicotyledon); as it begins to grow, it shows the development of a future shoot, called the plumule, and a future root, called the radicle.
The diagram shows a germinating gram seed. It highlights the main parts: the cotyledon (food store), the plumule (which will grow into the future shoot), and the radicle (which will grow into the future root).
In simple words: We soak gram seeds and then open them to see their parts. We'll find two food storage leaves (cotyledons), a tiny shoot (plumule), and a tiny root (radicle) that will grow later.

Exam Tip: When describing seed structure and germination, accurately label the cotyledons, plumule, and radicle, explaining their roles in embryonic development.

 

Gujarat Board Class 10 Science How do Organisms Reproduce? Textbook Questions and Answers

 

Question 1. Asexual reproduction takes place through budding in
(a) amoeba.
(b) yeast.
(c) plasmodium.
(d) leishmania.
Answer: (b) yeast.
In simple words: Budding is a way new life grows from a small part of the parent, and yeast commonly reproduces in this manner.

Exam Tip: Remember specific examples for each type of asexual reproduction, such as budding in yeast and Hydra, fission in Amoeba, and spore formation in fungi.

 

Question 2. Which of the following is not a part of the female reproductive system in human beings?
(a) Ovary
(b) Uterus
(c) Vas deferens
(d) Fallopian tube
Answer: (c) Vas deferens
In simple words: The vas deferens is a tube found in males, used for sperm transport, so it is not part of the female reproductive system.

Exam Tip: Be familiar with the structures of both male and female reproductive systems to correctly identify parts unique to each.

 

Question 3. The anther contains -
(a) sepals
(b) ovules
(c) carpel
(d) pollen grains
Answer: (d) pollen grains
In simple words: The anther is the part of a flower that produces and holds the pollen grains, which are necessary for plant reproduction.

Exam Tip: Recall the parts of a flower and their functions, especially focusing on the male reproductive organ (stamen) and its components like the anther and pollen.

 

Question 4. What are the advantages of sexual reproduction over asexual reproduction?
Answer: In asexual reproduction, the offspring is nearly identical to the parent, as they share the same genetic material. Therefore, little to no variation exists. Sexual reproduction, however, involves the joining of male and female gametes. The progeny shows a wide range of characteristics because they inherit genes from both the mother and the father. This blending of genes in diverse combinations leads to genetic differences. These variations promote the ongoing evolution of different species and the creation of various organisms.
In simple words: Sexual reproduction is better because it mixes genes from two parents, creating unique offspring with differences. These differences help species adapt and change over time, which asexual reproduction (making exact copies) doesn't do.

Exam Tip: Emphasize genetic variation and its role in adaptation and evolution as the main advantages of sexual reproduction.

 

Question 5. What are the functions performed by testis in human beings?
Answer: The role of the testis is to generate sperm and the male sex hormone, which is known as testosterone.
In simple words: The testis has two main jobs: making sperm for reproduction and producing the male hormone, testosterone.

Exam Tip: State both primary functions: gamete (sperm) production and hormone (testosterone) secretion, which is responsible for male secondary sexual characteristics.

 

Question 6. Why does menstruation occur?
Answer: Menstruation happens in females when the egg released by the ovary is not fertilized. Because the egg does not combine with a male gamete, the uterus no longer needs its thick, soft lining, which is rich in blood vessels. This unfertilized egg perishes within a day, and the uterine lining disintegrates, expelling blood and other tissues. This material then exits the body through the vagina as bleeding.
In simple words: Menstruation occurs because an egg released by the ovary isn't fertilized. When this happens, the uterus doesn't need its thick lining, so it breaks down and leaves the body as bleeding.

Exam Tip: Explain that menstruation is the shedding of the uterine lining when fertilization does not occur, providing the biological reason for the process.

 

Question 7. Draw a labelled diagram of the longitudinal section of a flower.
Answer:
The diagram displays a longitudinal section of a flower with key parts labeled:
* **Pistil:** Comprises the Stigma (top receptive part), Style (stalk connecting stigma to ovary), and Ovary (contains ovules).
* **Stamen:** Comprises the Anther (produces pollen) and Filament (stalk supporting anther).
* **Other parts:** Petal (often colorful, attracts pollinators) and Sepal (leaf-like structure enclosing the bud).
In simple words: This drawing shows the inner parts of a flower. You can see the parts that make seeds (pistil) and the parts that make pollen (stamen), along with petals and sepals.

Exam Tip: When drawing a flower, ensure clear labeling of all reproductive (pistil, stamen, anther, stigma, ovary) and accessory parts (petals, sepals) to show a complete understanding of its anatomy.

 

Question 8. What are the different methods of contraception?
Answer: Contraception refers to methods used to prevent pregnancy. Different methods of contraception include:
* **Physical Barrier Methods:** These involve using items like condoms, diaphragms, or cervical caps. They block sperm from entering the female reproductive tract, creating a physical barrier.
* **Chemical Methods:** Oral contraceptive pills are used to alter hormonal balance, which prevents the release of eggs. Vaginal pills can also be used to eliminate sperm.
* **Surgical Methods:** This category includes vasectomy in males (where the sperm duct is removed) and tubectomy in females (where a small part of the fallopian tube is removed).
In simple words: Contraception helps prevent pregnancy using different ways: physical barriers like condoms, chemical methods like birth control pills that stop eggs, and surgeries like vasectomy or tubectomy for permanent prevention.

Exam Tip: Categorize contraceptive methods (barrier, chemical, surgical) and provide a brief explanation and example for each, highlighting their mechanism of action.

 

Question 9. How are modes of reproduction different in unicellular and multicellular organisms?
Answer: Unicellular organisms consist of just one cell. They do not possess specialized tissues for reproduction. Consequently, they reproduce through processes like fission or budding. Multicellular organisms, on the other hand, are made of many different cells and have distinct systems dedicated to reproduction. Therefore, they can reproduce using both sexual and asexual methods.
In simple words: Single-celled organisms reproduce simply by splitting or budding because they lack special reproductive parts. Multi-celled organisms have many cells and special systems, so they can reproduce in more complex ways, both sexually and asexually.

Exam Tip: Contrast the simplicity of reproduction in unicellular organisms (direct cell division) with the more complex, specialized systems and varied methods (both sexual and asexual) in multicellular organisms.

 

Question 10. How does reproduction help in providing stability to the population of species?
Answer: Stability is achieved by balancing the rates of birth and death. Hence, the number of births should be roughly equivalent to the number of deaths.
In simple words: Reproduction keeps a species stable by making sure that about the same number of new individuals are born as old ones die, preventing the population from growing too much or shrinking too fast.

Exam Tip: Explain that reproduction maintains population stability by ensuring a balance between birth and death rates, preventing species extinction or overpopulation.

 

Question 11. What could be the reasons for adopting contraceptive methods?
Answer: The reasons for choosing contraceptive methods might include:
* Protection against sexually transmitted infections like HIV-AIDS, gonorrhea, syphilis, and warts.
* Limiting the total number of children.
* Allowing enough time between one birth and the next.
* Maintaining healthy reproductive well-being.
* Managing population growth.
In simple words: People use contraception to prevent STDs, control family size, space out births, keep their reproductive health good, and help manage the overall population.

Exam Tip: List several key reasons for using contraception, including disease prevention, family planning, maternal health, and population management.

 

Gujarat Board Class 10 Science How do Organisms Reproduce? Additional Important Questions and Answers

 

Short Answer Type Questions

 

Question 1. Why do organisms reproduce?
Answer: Organisms reproduce to continue their lineage and keep their species existing.
In simple words: Organisms reproduce so their kind doesn't die out and to keep their species alive.

Exam Tip: State that reproduction ensures the continuation of the species and the passing on of genetic information to future generations.

 

Question 2. How do we Know that two different individual belong to the same species?
Answer: Individuals are considered to be of the same species if they can interbreed and produce fertile offspring, along with showing similarities in their body structure and other physical characteristics.
In simple words: We know two individuals are the same species if they can breed together and have babies that can also have babies, and if they look very similar.

Exam Tip: The key criterion for identifying members of the same species is their ability to interbreed and produce fertile offspring, alongside observable physical similarities.

 

Question 3. Name the nucleic acids.
Answer: DNA and RNA are the two nucleic acids found in living cells.
In simple words: The two main nucleic acids are DNA and RNA.

Exam Tip: Simply list the full names of both nucleic acids: Deoxyribonucleic Acid (DNA) and Ribonucleic Acid (RNA).

 

Question 4. Give the full form of DNA.
Answer: Deoxyribonucleic Acid.
In simple words: DNA stands for Deoxyribonucleic Acid.

Exam Tip: Make sure to spell out the full name correctly: Deoxyribonucleic Acid.

 

Question 5. What happens during copying of DNA?
Answer: During DNA copying, new duplicates of DNA are created, and genetic information is transferred from one generation to the subsequent one.
In simple words: When DNA copies itself, it makes new identical DNA strands, ensuring that genetic information moves from parent to offspring.

Exam Tip: Focus on the two main outcomes: the creation of new DNA copies and the transmission of genetic traits to the next generation.

 

Question 6. When does copying of DNA occur?
Answer: DNA replication happens during the process of cell division.
In simple words: DNA copies itself when a cell is getting ready to divide into new cells.

Exam Tip: State clearly that DNA replication is an essential event that takes place before cell division, ensuring each new cell receives a complete set of genetic material.

 

Question 7. The mode of reproduction depends on which feature of the organism.
Answer: The way an organism reproduces is determined by its overall body structure.
In simple words: How an organism reproduces depends on what its body looks like and how it is built.

Exam Tip: Understand that simpler organisms often use simpler reproductive methods, while complex organisms have more specialized systems due to their body design.

 

Question 8. Name two plants whose flowers are unisexual.
Answer: Papaya and watermelon are two plants with unisexual flowers.
In simple words: Papaya and watermelon plants have flowers that are either male or female, not both.

Exam Tip: Remember examples of plants with unisexual flowers (male and female flowers on separate or the same plant) versus bisexual flowers (both parts in one flower).

 

Question 9. Name two plants whose flowers are bisexual.
Answer: Mustard and china rose are two plants whose flowers are bisexual.
In simple words: Mustard and china rose plants have bisexual flowers, meaning each flower has both male and female parts.

Exam Tip: Provide specific examples of plants whose flowers contain both male (stamen) and female (pistil) reproductive parts.

 

Question 10. What is fertilization?
Answer: Fertilization is the process where male and female gametes combine.
In simple words: Fertilization is when the male and female reproductive cells join together to start new life.

Exam Tip: Define fertilization as the fundamental event of sexual reproduction: the successful fusion of male and female gametes to form a zygote.

 

Question 11. What is pollination?
Answer: Pollination is the action of moving pollen grains from the stamen to the stigma of a flower.
In simple words: Pollination is when pollen moves from one part of a flower (stamen) to another part (stigma), which helps plants make seeds.

Exam Tip: Clearly state that pollination involves the transfer of pollen, specifying the source (stamen/anther) and destination (stigma) within a flower.

 

Question 12. What is the importance of DNA copying in reproduction?
Answer: During reproduction, DNA replication is crucial for transmitting traits from parents to their offspring.
In simple words: DNA copying is important in reproduction because it passes on traits and characteristics from parents to their children.

Exam Tip: Highlight that DNA copying ensures genetic continuity and the inheritance of parental traits by the next generation.

 

Question 13. How does the developing embryo get nourishment inside the mother's body?
Answer: The embryo receives nutrients from the mother's blood through a specialized tissue known as the placenta.
In simple words: The growing embryo gets food from the mother's blood, using a special part called the placenta to take in nutrients.

Exam Tip: Identify the placenta as the primary organ responsible for nutrient and waste exchange between the mother and the developing embryo.

 

Question 14. What are the structural changes observed in the flower after fertilization?
Answer: After fertilization, the calyx and corolla fade and drop off, and the stamens also fall away. The ovary then develops into the fruit. The ovule inside the ovary transforms into a seed. Once the seed fully matures, the fruit often dries up, allowing for the scattering of seeds.
In simple words: After fertilization, the flower parts like petals and stamens fall off. The ovary grows into a fruit, and the ovules inside become seeds. The fruit then dries, helping the seeds spread.

Exam Tip: Describe the fate of each floral part: sepals, petals, stamens wither; ovary becomes fruit; ovules become seeds. Also mention the eventual dispersal of seeds.

 

Question 15. What do you mean by Sexual Dimorphism?
Answer: Sexual dimorphism refers to the physical differences between males and females of the same species, which cause them to look distinct from one another.
In simple words: Sexual dimorphism means that males and females of the same animal or plant species look different from each other, beyond just their reproductive organs.

Exam Tip: Define sexual dimorphism as observable physical differences between sexes of a species, providing examples like plumage color in birds or antler size in deer if applicable.

 

Short Answer Type Questions

 

Question 1. Differentiate between asexual and sexual reproduction.
Answer:
**Asexual:**
* Asexual reproduction includes only one parent.
* No reproductive cells (gametes) are created during asexual reproduction.
* Few or no genetic differences arise during asexual reproduction.
**Sexual:**
* Sexual reproduction involves two parents (a male and a female).
* The formation of gametes occurs in sexual reproduction.
* Numerous variations are common during sexual reproduction.
In simple words: Asexual reproduction uses one parent, makes no gametes, and has little variation. Sexual reproduction uses two parents, makes gametes, and creates many variations.

Exam Tip: Use a clear point-by-point comparison, highlighting differences in the number of parents, gamete involvement, and the presence/absence of genetic variation.

 

Question 2. Enumerate the various methods of asexual reproduction in living organisms.
Answer: The different ways asexual reproduction happens in living organisms are: fission (both binary and multiple), fragmentation, regeneration, budding, vegetative propagation, spore formation, and tissue culture.
In simple words: Asexual reproduction happens in ways like splitting (fission), breaking into pieces (fragmentation), regrowing parts (regeneration), growing a new bud (budding), growing from plant parts (vegetative propagation), making spores, or through tissue culture.

Exam Tip: List all common methods of asexual reproduction clearly, ensuring you recall distinct examples for each method.

 

Question 3. What is binary and multiple fission? Name the organisms in which they occur.
Answer: Binary fission is the process where a single parent cell divides into two identical daughter cells. This occurs in organisms like Amoeba, Paramecium, Euglena, and other protozoa. In multiple fission, a single-celled organism splits into many daughter cells while enclosed within a protective cyst. These new cells are then released when the cyst ruptures. This process occurs in Plasmodium (the malarial parasite).
In simple words: Binary fission is when one cell splits into two, like in Amoeba. Multiple fission is when one cell splits into many inside a protective case, like in Plasmodium.

Exam Tip: Define both binary and multiple fission distinctly, and provide specific examples of organisms that exhibit each type of reproduction.

 

Question 4. What is fragmentation?
Answer: Fragmentation is a reproductive method where an organism breaks apart into smaller pieces or fragments, and each piece then develops into a new, complete organism, as seen in the algae Spirogyra.
In simple words: Fragmentation means an organism breaks into smaller parts, and each part grows into a whole new organism, like what happens with Spirogyra algae.

Exam Tip: Define fragmentation as a form of asexual reproduction where a parent organism breaks into fragments, each developing into a new individual, and give a clear example.

 

Question 5. What is regeneration? Name two organisms that can reproduce by regeneration.
Answer: Regeneration is the capacity of many fully developed organisms to form new individuals from their body parts if they are cut or broken into several pieces. However, not all organisms possess this ability to regenerate. Hydra and Planaria are two organisms that can reproduce through regeneration.
In simple words: Regeneration is when an animal can regrow a whole new body from a piece of itself if it gets cut. Not all animals can do this, but Hydra and Planaria are two examples that can.

Exam Tip: Define regeneration as the ability to regrow lost body parts or an entire organism from a fragment. Provide specific examples like Hydra and Planaria.

 

Question 6. What is budding? Name two organisms that reproduce asexually by budding.
Answer: Budding is a process where a small portion of the parent's body grows outwards as a bud, which later separates and develops into a new organism. Hydra and yeast are two organisms that reproduce asexually through budding.
In simple words: Budding is when a small new part grows out of a parent, breaks off, and becomes a new, separate organism. Hydra and yeast use budding to reproduce.

Exam Tip: Define budding as the formation of a new individual from an outgrowth or bud on the parent body. Provide two clear examples like Hydra and yeast.

 

Question 7. What is vegetative propagation? What are its advantages?
Answer: Vegetative propagation is the natural process where certain plants reproduce asexually using their vegetative parts, such as roots, stems, and leaves. This method offers several benefits. Plants grown through vegetative propagation can produce flowers and fruits sooner than those grown from seeds. It also allows for the propagation of plants that have lost the ability to produce seeds, such as banana, rose, and jasmine. All new plants generated by this method are genetically identical to the original parent plant.
In simple words: Vegetative propagation is when new plants grow from parts of an old plant (like stems or leaves), not seeds. Its advantages are faster growth, earlier flowers and fruits, and being able to grow plants that don't make seeds.

Exam Tip: Define vegetative propagation clearly and list its advantages, such as faster plant development, suitability for seedless plants, and genetic uniformity.

 

Question 8. How do potato and Bryophyllum plants reproduce vegetatively?
Answer: Potato tubers have small indentations called 'eyes' on their surface. These 'eyes' contain vegetative buds that can sprout to produce a new potato plant. Likewise, the thick leaves of Bryophyllum have vegetative buds located in the notches along their edges. These buds then grow into small plantlets, which form new plants once they detach.
In simple words: Potatoes reproduce from 'eyes' which are buds on their surface. Bryophyllum reproduces from buds found along the edges of its leaves. Both form new plants from these buds.

Exam Tip: Describe the specific vegetative structures (eyes/buds) and locations (tuber surface, leaf margins) for both potato and Bryophyllum, explaining how they lead to new plant formation.

 

Question 9. Name two plants that can reproduce asexually by formation of spores.
Answer: Bread mould (Rhizopus) and ferns both reproduce asexually by creating spores.
In simple words: Bread mould and ferns are two plants that make new plants using spores.

Exam Tip: Provide clear examples of organisms that utilize spore formation as their primary method of asexual reproduction.

 

Question 10. What are the limitations of asexual mode of reproduction?
Answer: In the asexual method of reproduction, there is no genetic variation, which results in less adaptability in the offspring. This means the new organisms might not cope well with changing environments.
In simple words: Asexual reproduction makes exact copies, so there's no genetic change. This means the offspring can't adapt easily if conditions change.

Exam Tip: Remember that lack of variation is a key disadvantage of asexual reproduction, as it reduces the species' ability to survive environmental changes.

 

Question 11. What is the significance of sexual reproduction?
Answer:

• Sexual reproduction leads to new combinations of characters and boosts genetic variations.
• It encourages a wide range of characteristics among the offspring.
• This process quickens the rate at which variations appear in a population.

In simple words: Sexual reproduction mixes up genes, which creates new combinations and increases differences among offspring. This helps populations evolve faster and adapt better.

Exam Tip: Highlighting genetic variation and evolution is crucial when discussing the importance of sexual reproduction.

 

Question 12. How is the amount of DNA maintained in each generation?
Answer: The amount of DNA is kept constant in each generation by a specialized process of cell division called meiosis. This process creates unique male and female germ cells, also known as gametes, which are haploid (contain half the chromosome number). When a male gamete and a female gamete fuse during fertilization, they form a diploid zygote, which has the same number of chromosomes as the parent. This entire process ensures that the chromosome count and the total amount of DNA remain stable across generations.
In simple words: DNA levels stay constant because special cells called gametes (sperm and egg) have half the normal DNA. When they join, they make a new cell with the full, correct amount of DNA, just like the parents.

Exam Tip: Clearly explain the roles of meiosis, gametes (haploid), fertilization, and zygote (diploid) in maintaining chromosome number and DNA quantity.

 

Question 13. State the advantages of seed formation in plants.
Answer: A seed holds the future plant or embryo, which can grow into a seedling if conditions are appropriate. Seeds are in a dormant state, allowing them to be kept in a protected condition for a long period. This protects the embryo and helps in dispersal.
In simple words: Seeds protect a tiny plant inside and can wait a long time before growing. They also help plants spread to new places.

Exam Tip: Focus on seed protection, dormancy, and dispersal as key advantages.

 

Question 14. What is germination of seed?
Answer: When a seed obtains the right conditions, the embryo inside it begins to grow and form the shoot and the root. When the embryo emerges from the seed to form a new seedling, this process is called germination of seed.
In simple words: Seed germination is when the tiny plant inside a seed starts growing into a shoot and a root when it gets the right conditions, pushing out of the seed coat.

Exam Tip: Define germination as the process where the embryo grows into a seedling and emphasize the "right conditions" needed.

 

Question 15. What is puberty?
Answer: Puberty is the age when gametes start forming in human males and females. At this age, boys and girls become sexually mature.
In simple words: Puberty is the time in life when boys and girls become able to have children because their bodies start making reproductive cells.

Exam Tip: Define puberty as the onset of sexual maturity and gamete formation.

 

Question 16. What changes occur in the flower after fertilisation?
Answer: After fertilization, the flower parts begin to wither. The sepals and petals dry up, the ovary changes into a fruit, the ovule develops into a seed, and the zygote forms the embryo, which is encased within the seed.
In simple words: After a flower is fertilized, its petals and sepals wilt. The ovary turns into fruit, the ovules become seeds, and the fertilized egg inside becomes an embryo, which is protected by the seed.

Exam Tip: List the transformations of specific floral parts (sepals, petals, ovary, ovule, zygote) into their post-fertilization structures.

 

Question 17. Name the agents of pollination.
Answer: The agents that assist in pollination include wind, water, birds, and insects.
In simple words: Wind, water, birds, and insects are the main things that help pollen move from one flower to another.

Exam Tip: Remember the common biotic and abiotic agents of pollination.

 

Question 18. State the functions of the human male and female sex hormones.
Answer: The human male sex hormone, testosterone, regulates the creation of male gametes (sperms) and triggers changes in appearance seen in boys during puberty. The human female sex hormone, estrogen, causes the changes that occur in girls during puberty, and progesterone manages uterine changes during the menstrual cycle and helps in maintaining pregnancy.
In simple words: Testosterone in males makes sperm and causes male puberty changes. Estrogen in females causes female puberty changes, and progesterone controls the uterus during the menstrual cycle and helps with pregnancy.

Exam Tip: Distinguish the roles of testosterone (sperm production, male secondary characteristics) from estrogen (female secondary characteristics) and progesterone (menstrual cycle, pregnancy maintenance).

 

Question 19. What happens when the egg is fertilised?
Answer: When the egg is fertilized, a zygote is formed, which then starts dividing and becomes implanted in the lining of the uterus. This implantation is the first step towards pregnancy.
In simple words: When an egg is fertilized, it becomes a zygote, starts dividing, and attaches itself to the uterus wall.

Exam Tip: Focus on the formation of the zygote and its implantation in the uterus.

 

Question 20. What is menstruation? Why does it occur?
Answer: Menstruation is the process where the inner lining of the uterus, along with blood vessels, breaks down and is removed from the body as vaginal bleeding. This occurs approximately every 28 days if the egg is not fertilized. It happens in human females and some other primates.
In simple words: Menstruation is when the uterus lining sheds blood and tissue because an egg wasn't fertilized. This happens monthly in females.

Exam Tip: Explain menstruation as the shedding of the uterine lining and link its occurrence to the absence of fertilization.

 

Question 21. What is STD? Name two STDs.
Answer: STD stands for Sexually Transmitted Disease. Two examples of STDs are syphilis and gonorrhoea.
In simple words: STD means Sexually Transmitted Disease. Syphilis and gonorrhoea are two examples.

Exam Tip: Provide the full form of STD and list two common examples.

 

Question 22. What is the role of seminal vesicles and prostate gland?
Answer: The seminal vesicles and prostate gland are accessory glands connected with the male reproductive system. These glands release a fluid that helps in the transport of sperms and offers nourishment to the sperms. This fluid, along with the sperms, forms the semen.
In simple words: Seminal vesicles and the prostate gland make fluids that help sperm travel and give them nutrients, creating semen.

Exam Tip: Highlight their function in sperm transport, nourishment, and contributing to semen formation.

 

Question 23. Draw a well labelled diagram of a dicot seed (gram seed).
Answer: The diagram shows the germination of a gram seed. It illustrates the structure of a dicotyledonous seed with its key parts labeled:

• Cotyledon (food store): Two large parts that store food for the embryo.
• Plumule (future shoot): The embryonic shoot that develops into the stem and leaves.
• Radicle (future root): The embryonic root that develops into the root system.

In simple words: A dicot seed has two food storage parts (cotyledons), a tiny shoot (plumule) that will become the plant's stem, and a tiny root (radicle) that will become the plant's root.

Exam Tip: When asked to draw, clearly label all essential parts of the dicot seed (cotyledon, plumule, radicle) and indicate their future roles.

 

Question 24. Device an experiment to show germination of gram seed.
Answer:

1. Soak a few gram seeds (chana) and keep them overnight in water.
2. Drain the extra water and cover the seeds with a wet cloth, leaving them for a day. Make sure the seeds do not become dry.
3. Carefully cut open the seeds and observe the various parts.
4. Compare your observations with a diagram showing gram seed germination to identify all the parts. This helps understand how the plumule and radicle emerge from the seed.

In simple words: To see a gram seed sprout, soak it overnight, then wrap it in a damp cloth for a day. After that, open it up and look at its parts to see how it starts to grow.

Exam Tip: Clearly outline each step of the experiment, focusing on maintaining moisture and careful observation to identify parts.

 

Question 25. Draw a well labelled diagram of a bisexual flower.
Answer: The diagram illustrates a bisexual flower, showcasing its male and female reproductive parts. Key labels include:

• Pistil: The female reproductive part, comprising:
  • Stigma: The receptive tip for pollen.
  • Style: The stalk connecting the stigma to the ovary.
  • Ovary: Contains ovules.
• Stamen: The male reproductive part, comprising:
  • Anther: Produces pollen.
  • Filament: Supports the anther.
• Petal: Often brightly colored parts to attract pollinators.
• Sepal: Leaf-like structures that protect the bud.

In simple words: A bisexual flower has both male parts (stamen with anther and filament) and female parts (pistil with stigma, style, and ovary), along with petals and sepals.

Exam Tip: Ensure your diagram clearly labels all major parts of a bisexual flower, distinguishing between male (stamen) and female (pistil) reproductive organs, as well as accessory structures (sepals, petals).

 

Question 26. State the changes that occur in human males and females at puberty.
Answer: In human males, puberty brings about changes such as hair growth on the body, the appearance of a beard and moustache, and a deepening of the voice, making it hoarse. In females, puberty shows the development of breasts and the beginning of menstruation.
In simple words: At puberty, boys grow body hair, facial hair, and their voice deepens. Girls develop breasts and start their menstrual periods.

Exam Tip: List specific secondary sexual characteristics for both males and females during puberty.

 

Question 27. What is self and cross pollination?
Answer:
Self Pollination - This is when pollen grains transfer from the anther of a flower to the stigma of the same flower or another flower on the same plant.
Cross Pollination - This involves the transfer of pollen grains from the anther of a flower to the stigma of another flower on a different plant of the same species.
In simple words: Self-pollination happens when pollen moves within the same flower or to another flower on the same plant. Cross-pollination is when pollen moves between flowers on different plants of the same type.

Exam Tip: Differentiate self and cross-pollination clearly by specifying whether pollen transfer occurs within the same plant or between different plants of the same species.

 

Question 28.
(a) Name the parts labelled A, B, C, D, and E
(b) Where do the following functions occurs?
(i) Production of an egg
(ii) Fertilisation
(iii) Implantation of zygote
(c) What happens to the lining of uterus
(i) before release of fertilised egg.
(ii) if no fertilisation occurs.
Answer:
(a)

• A → Fallopian tube
• B → Ovary
• C → Uterus
• D → Cervix
• E → Vagina

(b)

• Production of an egg – ovary
• Fertilisation – fallopian tubes
• Implantation of zygote – lining of the uterus

(c)

• Before release of fertilized egg – the uterus wall becomes thick.
• If no fertilisation occurs – the lining of uterus slowly breaks down and comes out in the form of bleeding.

In simple words: For part (a), A is the fallopian tube, B is the ovary, C is the uterus, D is the cervix, and E is the vagina. For part (b), eggs are made in the ovary, fertilization happens in the fallopian tubes, and the fertilized egg attaches to the uterus lining. For part (c), before a fertilized egg is released, the uterus wall gets thick. If no fertilization happens, the uterus lining gradually breaks down and leads to bleeding.

Exam Tip: Be precise in identifying all labelled parts and linking each reproductive function to its correct anatomical location. For the uterus lining, describe both scenarios: preparing for implantation and shedding if no fertilization occurs.

 

Question 29. What is the role of following in reproduction?
1. DNA
2. Ovulation
3. Fertilisation
4. Puberty
5. Contraception
Answer:
1. Variation
2. Egg production
3. Zygote formation
4. Attainment of sexual maturity
5. Birth control
In simple words: DNA helps create differences, ovulation produces eggs, fertilization forms a zygote, puberty brings sexual maturity, and contraception helps control births.

Exam Tip: For each term, provide a concise explanation of its specific role in the reproductive process.

 

Question 30. Explain the process of sexual reproduction in plants.
Answer: After pollen lands on a suitable stigma, it grows to form a pollen tube. This pollen tube moves through the style and carries the male germ cells. The pollen tube then enters the ovule, and the male germ cells fuse with the egg cell to form the zygote. This process is called fertilization.
In simple words: In plants, sexual reproduction starts when pollen lands on the stigma and grows a tube down to the ovule. The male cells travel through this tube to join with the egg cell, creating a new seed in a process called fertilization.

Exam Tip: Describe the journey of pollen, pollen tube formation, and the fusion of male and female gametes within the ovule to explain plant sexual reproduction.

 

Question 31. What is the mode of reproduction in amoeba when the condition is unfavourable?
Answer: When conditions become unfavorable, such as lack of food, moisture, or suitable temperature, amoeba undergoes mitotic cell division. The organism develops a thick protective coating around itself called a cyst. This cyst helps the organism stay protected in difficult conditions. The nucleus divides into several new nuclei, and each daughter nucleus is then surrounded by a membrane. All metabolic activities stop in the organism after cyst formation. When favorable conditions return, the cyst breaks open, releasing the daughter nuclei, which then grow into new individuals. Plasmodium and amoeba both undergo a cyst stage when they are not inside the body of their primary host, such as humans.
In simple words: When conditions are bad, an amoeba forms a tough outer shell called a cyst. Inside, its nucleus divides many times. When conditions improve, the cyst breaks open, releasing many new amoebas.

Exam Tip: Explain cyst formation, multiple nuclear divisions within the cyst, and the release of daughter nuclei upon return of favorable conditions.

 

Question 32. Explain the structure of seed.
Answer: A seed contains an embryo, some stored food, and is covered by a protective seed coat. The stored food is kept in the cotyledons. The embryo has two distinct pointed parts: the upper part, called the plumule, which develops into the shoot system, and the lower part, called the radicle, which develops into the root system. Cotyledons supply food when the embryo needs it during germination. Seed germination is the process by which the embryo inside the seed starts a new life.
In simple words: A seed has a baby plant (embryo), food stored in cotyledons, and a hard protective coat. The embryo has a tiny shoot (plumule) and a tiny root (radicle) that grow when the seed sprouts.

Exam Tip: Detail the key components of a seed (embryo, reserve food, seed coat, cotyledons, plumule, radicle) and their functions, especially during germination.

 

Question 33. Name the following:
1. Name two plants that cannot produce seeds.
2. An organism that reproduces by budding and regeneration.
3. An organism that grows by multiple fission
4. One unisexual flower.
Answer:
1. Bryophyllum, Banana
2. Hydra
3. Paramecium
4. Maize flower
In simple words: Bryophyllum and Banana don't make seeds. Hydra reproduces by budding and growing new parts. Paramecium reproduces by splitting into many. Maize flowers have only one type of reproductive organ.

Exam Tip: Provide accurate examples for each reproductive characteristic or plant type.

 

Question 34. What does the male and female reproductive system consists of?
Answer: The male reproductive system in human beings includes the testes (which make sperms), vas deferens, seminal vesicles, prostate gland, urethra, and penis. The female reproductive system consists of a pair of ovaries, fallopian tube, uterus, and vagina.
In simple words: The male system has testes, vas deferens, seminal vesicles, prostate gland, urethra, and penis. The female system has ovaries, fallopian tubes, uterus, and vagina.

Exam Tip: List all major organs of both the male and female human reproductive systems accurately.

 

Question 35. Give one term for the following:
1. Beginning of menstrual cycle
2. Release of ovum from the ovary
3. Fusion of male and female eggs
4. Prevention of unwanted pregnancy
5. Time for development of offspring in female human.
Answer:
1. Menstruation
2. Ovulation
3. Fertilisation
4. Contraception
5. Nine months
In simple words: The start of the monthly period is menstruation. When an egg leaves the ovary, it's ovulation. Male and female egg joining is fertilization. Stopping unwanted pregnancy is contraception. The time a baby grows inside is nine months.

Exam Tip: Provide the single, correct biological term for each given definition.

 

Long Answer Type Questions

 

Question 1. Draw a well labelled diagram of the female reproductive system in humans.
Answer: The diagram illustrates the female reproductive system with the following key parts:

• Oviduct or Fallopian tube: Tubes connecting the ovaries to the uterus, where fertilization often occurs.
• Ovary: Produces eggs and female hormones.
• Uterus: A muscular organ where a fertilized egg implants and develops.
• Cervix canal: The passage through the cervix.
• Cervix: The lower, narrow part of the uterus that opens into the vagina.
• Vagina: The muscular tube connecting the uterus to the outside of the body.

In simple words: The female reproductive system includes the ovaries (which make eggs), fallopian tubes (where eggs travel), the uterus (where a baby grows), the cervix, and the vagina.

Exam Tip: When drawing, clearly label the ovaries, fallopian tubes (oviducts), uterus, cervix, and vagina, as these are the primary components of the female reproductive system.

 

Question 2. With the help of diagrams explain the process of budding in Hydra and fission in Amoeba.
Answer:
Fission in Amoeba:Fission in Amoeba begins with a parent cell. The nucleus first elongates and then divides into two parts (karyokinesis). Following this, the cytoplasm also divides (cytokinesis) to form a constriction, eventually leading to the formation of two smaller, identical daughter amoebae cells.
Budding in Hydra:Budding in Hydra starts with a small bud growing out from the parent Hydra's body. The nucleus of the parent Hydra divides, and one of the new nuclei moves into the bud. As the bud develops, it gains its own structures and eventually detaches from the parent, becoming a new, independent Hydra.
In simple words: Amoeba reproduces by fission, where one cell splits into two identical new cells after its nucleus divides. Hydra reproduces by budding, where a small outgrowth, or bud, grows on the parent, develops into a new Hydra, and then breaks off.

Exam Tip: For fission in Amoeba, describe the division of the nucleus (karyokinesis) followed by the division of the cytoplasm (cytokinesis) leading to two daughter cells. For budding in Hydra, explain the outgrowth of a bud, nuclear migration, and eventual detachment to form a new individual.

 

Question 3. State the functions of the following:
(a) testis
(b) ovaries
(c) vas deferens
(d) stamen
(e) pistil
Answer:
(a) Testis – Testes create male gametes (sperms) and produce the male sex hormone testosterone.
(b) Ovaries – Ovaries form the female gamete (ovum or egg cell) and secrete the female sex hormones estrogen and progesterone.
(c) Vas deferens – The vas deferens transport sperms from the testis to the outside of the body.
(d) Stamen - Stamens create pollen grains in flowers. These pollen grains contain the male gametes.
(e) Pistil - The pistil's ovary creates the egg, and the stigma helps attract pollen grains for fertilization.
In simple words: Testes make sperm and male hormones. Ovaries make eggs and female hormones. Vas deferens move sperm. Stamens make pollen in flowers. The pistil's ovary makes eggs, and its stigma catches pollen for fertilization.

Exam Tip: Be specific about both the reproductive products (gametes) and the hormonal secretions for gonads, and the transport/pollination roles for ducts and floral parts.

 

Question 4. What are the various artificial methods of vegetative propagation in plants?
Answer: The various artificial methods of vegetative propagation in plants are:
(a) Cutting – In this method, any part of the plant, such as the stem, root, or leaf, is cut and planted in the soil. This piece then grows into a new plant, as seen in rose, guava, and grapes.
(b) Layering – In plants like jasmine and strawberry, a branch from the plant is bent down to the ground and covered with damp soil. After a few days, new roots appear, and the branch is then cut from the main plant.
(c) Grafting - In this technique, the stem of one plant is cut, and another plant's stem is joined onto it. This is used for agricultural purposes in plants like sugarcane, roses, and grapes.
(d) By Roots – Plants such as sweet potato can grow more plants from their roots.
(e) Stem – Plants like potato, ginger, and onion show growth from their stems or modified stems.
(f) By Buds – Plants like Bryophyllum and potato grow small buds on them, which develop into new plants.
In simple words: Plants can be grown artificially in several ways: cutting a part of the plant and planting it (like roses), bending a branch into soil to grow roots (layering), joining parts of two plants together (grafting), or growing new plants from roots (sweet potato), stems (potato, ginger), or buds (Bryophyllum).

Exam Tip: Describe each method clearly with a relevant example, focusing on how a new plant is generated from a vegetative part.

 

Question 5.
(a) Name the human male reproductive organ that produces sperms and also secretes a hormone. Write the functions of the secreted hormone.
(b) Name the parts of the human female reproductive system where (i) fertilisation takes place, and (ii) implantation of the fertilised egg occurs.
Explain how the embryo gets nourishment inside the mother's body.
Answer:
(a) Testis - The testis secretes the male hormone, testosterone.
Functions:

• Formation of sperms
• Development of secondary sexual characters.

(b)

• Fallopian tube / oviduct
• Uterus

Placenta is a special, disc-like tissue embedded in the mother's uterine wall, connected to the foetus/embryo. The placenta offers a large surface area for glucose, oxygen, and nutrients to pass from the mother's blood to the embryo/foetus.
In simple words: (a) The testis makes sperm and the hormone testosterone, which helps sperm form and causes male body changes. (b) Fertilization happens in the fallopian tube, and the fertilized egg attaches to the uterus. The embryo gets food and oxygen from the mother's blood through a special tissue called the placenta, which is like a bridge between them.

Exam Tip: For part (a), identify the testis and list the two main functions of testosterone. For part (b), name the correct locations for fertilization and implantation. For the nourishment, explain the role of the placenta as the connection between mother and embryo for nutrient and gas exchange.

 

Practical Based Questions (Solved)

 

Question 1. Name two organisms each which can reproduce asexually by (i) fission and (ii) by budding.
Answer:

• By Fission: amoeba, paramecium
• By budding: yeast and Hydra

In simple words: Amoeba and paramecium reproduce by fission. Yeast and Hydra reproduce by budding.

Exam Tip: Provide accurate examples for each method of asexual reproduction.

 

Question 2. During the asexual reproduction of amoeba the first stage is karyokinesis and second stage is cytokinesis. Explain the two stages.
Answer: Karyokinesis is the process where the nucleus divides. It corresponds to the separation of daughter chromosomes into two daughter nuclei. Karyokinesis is generally followed by Cytokinesis. Cytokinesis is the process where the cytoplasm divides. It corresponds to the separation of the daughter nuclei into two daughter cells. Cytokinesis happens right after mitosis.
In simple words: In amoeba reproduction, karyokinesis is when the nucleus splits into two. Cytokinesis is when the rest of the cell, the cytoplasm, divides after the nucleus, making two new cells.

Exam Tip: Clearly define karyokinesis as nuclear division and cytokinesis as cytoplasmic division, explaining their sequence in cell reproduction.

 

Question 3. List any four observations one can make while studying the yeast cell showing reproduction.
Answer:

1. One or more bulb-like projections (buds) appear from the cell membrane.
2. The nucleus of the parent cell divides, and one of the daughter nuclei moves into the bud.
3. The bud eventually separates from the parent body and grows into a new individual.
4. The parent's identity is maintained in the process of budding.

In simple words: When yeast reproduces, you'll see small buds grow, the parent's nucleus split with one part going into the bud, the bud then breaking off to become a new yeast, and the parent cell staying itself.

Exam Tip: Describe the visible stages of budding: bud formation, nuclear division and migration, separation, and the parent's continued existence.

 

Question 4. List any four observations one can make while studying the amoeba slide showing reproduction.
Answer:

1. In this division, two similar individuals are formed from a single parent.
2. A mature Amoeba cell is typically larger. Its nucleus lengthens and gradually divides amitotically into two.
3. The division of the nucleus is followed by the division of the cytoplasm.
4. Thus, two new amoebae are formed from a single parent, and the parent's identity is lost as it becomes the two new individuals.

In simple words: When an amoeba reproduces, you'll see a single parent form two identical new amoebas. The parent's nucleus stretches and splits, then the cell body also splits, and the original parent is gone, replaced by the two new ones.

Exam Tip: Focus on the process of binary fission: the formation of two identical individuals, nuclear division, cytoplasmic division, and the 'loss' of the parent identity into the daughter cells.

 

Question 5. List the factors required for the seed to germinate.
Answer: Seeds require water, light, nutrients, a suitable substrate to grow in, and often an appropriate temperature for germination.
In simple words: For seeds to sprout, they need water, light, food, a place to grow, and usually a warm temperature.

Exam Tip: Enumerate the essential environmental conditions needed for successful seed germination.

 

Question 6. Name any three substrate one can use for the germination of seed.
Answer: The seeds can be germinated on wet cotton, soil, or cloth.
In simple words: You can sprout seeds on damp cotton, soil, or a wet cloth.

Exam Tip: Provide common and easily accessible materials used as germination substrates.