GSEB Class 9 Science Solutions Chapter 7 Diversity in Living Organisms

 

Question 1. Why do we classify organisms?
Answer: We classify organisms because it helps to:
1. Examine them correctly
2. Arrange them into different groups
3. Comprehend their connections and how they relate better
4. Anticipate the characteristics of a member based on the group it belongs to.
In simple words: We classify organisms to make it easier to study them, arrange them, understand their connections, and predict their traits based on their group.

Exam Tip: Focus on the key benefits of classification: organization, understanding relationships, and predicting characteristics for better understanding.

 

Question 2. Give three examples of the range of variations that you see in life forms around you.
Answer: The range of variations we observe in living forms around us includes:
1. Organisms come in many different colors (like flowers, birds), while some are white, clear, or without color (such as a cow or Amoeba).
2. The lifespan of various organisms also differs. Some exist for only a short period (for instance, mosquitoes), and some exist for many years (like a banyan tree).
3. The size of these organisms also differs, ranging from tiny micrometers (like bacteria) to huge plants and creatures (such as redwood trees in California or blue whales).
In simple words: We see many differences in living things. They can be different colors, have different lifespans (some live days, some live years), and come in different sizes, from very tiny to very large.

Exam Tip: When asked for examples, choose distinct categories like color, lifespan, and size to show a broad understanding of variations.

 

Question 3. Which do you think is a more basic characteristic for classifying organisms?
(a) the place where they live.
(b) the kind of cells they are made of. Why?
Answer:
(a) The more fundamental trait for classifying organisms is the kind of cells they are composed of.
(b) The reason for this is that various types of living things can inhabit or settle in the same environment, even though they are not part of the same category. For instance, various plants and animals populate forests. Therefore, habitat cannot be the more fundamental trait for grouping organisms.
In simple words: (a) The type of cells is more important. (b) This is because many different creatures can live in the same place but are not related. So, where they live isn't the best way to sort them.

Exam Tip: Emphasize that fundamental characteristics relate to intrinsic biological features (like cell type), while external factors (like habitat) can be misleading for classification.

 

Question 4. What is the primary characteristic on which the first division of organisms is made?
Answer: The main feature used to make the initial grouping of various organisms is the existence or non-existence of a clear nuclear membrane in them, meaning if they are prokaryotic or eukaryotic.
In simple words: The first big split in classifying living things is based on if their cells have a proper nucleus with a membrane or not. This sorts them into prokaryotes or eukaryotes.

Exam Tip: Remember that the presence or absence of a nuclear membrane is the fundamental distinction between prokaryotes and eukaryotes, forming the earliest division in classification.

 

Question 5. On what bases are plants and animals put into different categories?
Answer: Plants and animals are placed into different categories based on their:
1. How they get food: making their own (autotrophic) or consuming others (heterotrophic) and
2. Body structure: whether they have a cell wall or not.
In simple words: Plants and animals are grouped differently based on how they get their food (making it or eating it) and if their cells have a cell wall.

Exam Tip: The key distinctions between plants and animals for classification are their mode of nutrition (autotrophic vs. heterotrophic) and the presence or absence of a cell wall.

 

Question 6. Which organisms are called primitive and how are they different from the so-called advanced organisms?
Answer: Organisms with an old body structure (meaning they appeared earlier) are termed primitive, while organisms that have a more modern body structure (meaning they appeared later) are referred to as advanced organisms. For instance, Prokaryotes are considered primitive because they lack a well-defined nucleus, while eukaryotes are advanced as they possess a clear nucleus.
In simple words: Primitive organisms have simpler, older body plans, meaning they showed up earlier. Advanced organisms have newer, more complex body plans. For example, prokaryotes are primitive (no clear nucleus), and eukaryotes are advanced (have a clear nucleus).

Exam Tip: Understand that 'primitive' and 'advanced' in biology refer to evolutionary age and complexity of body design, not necessarily superiority.

 

Question 7. Will advanced organisms be the same as complex organisms? Why?
Answer: Yes, advanced organisms are generally the same as complex organisms. The intricacy of living things has grown throughout evolutionary time. More advanced organisms have developed a more complex body structure compared to primitive organisms. This increased intricacy often improves their ability to survive and thrive. Therefore, advanced organisms are considered complex.
In simple words: Yes, advanced organisms are usually complex organisms. Living things have become more complex over a long time. Advanced ones have more complicated bodies, which often helps them survive better.

Exam Tip: Explain that evolutionary advancement often correlates with increasing complexity, leading to better adaptation and survival.

 

Question 8. What is the criterion for classification of organisms as belonging to kingdom Monera or Protista?
Answer: All single-celled prokaryotes, which lack a clear nucleus and are without membrane-bound cell organelles, are placed in kingdom Monera. All single-celled eukaryotes, possessing a clear nucleus and membrane-bound organelles, are placed in kingdom Protista.
In simple words: Monera includes single-celled organisms without a proper nucleus or internal cell parts. Protista includes single-celled organisms that do have a proper nucleus and internal cell parts.

Exam Tip: Differentiate Monera and Protista primarily based on cell type (prokaryotic vs. eukaryotic) and the presence/absence of a well-defined nucleus and membrane-bound organelles.

 

Question 9. In which kingdom will you place an organism, which is single-celled, eukaryotic and photosynthetic?
Answer: Kingdom Protista.
In simple words: An organism that is single-celled, has a proper nucleus, and makes its own food through photosynthesis belongs in Kingdom Protista.

Exam Tip: Recall that Protista includes diverse eukaryotic organisms, many of which are unicellular and photosynthetic, like algae.

 

Question 10. In the hierarchy of classification, which grouping will have the smallest number of organisms with a maximum of characteristics in common and which will have the largest number of organisms?
Answer: Species will have the fewest organisms sharing the most common traits, and Kingdom will have the greatest number of organisms.
In simple words: In classification, a 'species' has the fewest organisms but they are very much alike. A 'kingdom' has the most organisms, but they are less alike.

Exam Tip: Understand the hierarchy of classification: Kingdom > Phylum > Class > Order > Family > Genus > Species. As you go down, the number of organisms decreases, but common characteristics increase.

 

Question 11. Which division among plants has the simplest organisms?
Answer: Thallophyta
In simple words: Among plant divisions, Thallophyta contains the simplest organisms.

Exam Tip: Recall that Thallophyta (algae) are the simplest plant-like organisms with undifferentiated body structures.

 

Question 12. How are pteridophytes different from the phanerogams?
Answer: Pteridophytes are cryptogams as they possess unnoticeable and concealed reproductive parts. They produce exposed embryos known as spores. Phanerogams, in contrast, have clearly distinct reproductive parts and produce embryos enclosed within the seed.
In simple words: Pteridophytes have hidden reproductive parts and make spores. Phanerogams have clear reproductive parts and make seeds with embryos inside.

Exam Tip: The primary distinction is that Pteridophytes reproduce via spores (cryptogams) with hidden organs, while Phanerogams reproduce via seeds (phanerogams) with visible, differentiated organs.

 

Question 13. How do gymnosperms and angiosperms differ from each other?
Answer: Gymnosperms are plants that do not flower, with reproductive parts found in cones. They produce exposed seeds, meaning the seeds are not covered by a fruit. Angiosperms are plants that flower, with reproductive parts located in flowers, and they produce seeds that are contained within a fruit.
In simple words: Gymnosperms do not make flowers and have 'naked' seeds, not inside a fruit. Angiosperms make flowers and their seeds are found inside a fruit.

Exam Tip: The key difference lies in seed enclosure: Gymnosperms have naked seeds (e.g., conifers), while Angiosperms have seeds enclosed within a fruit (e.g., apples, beans).

 

Question 14. How do poriferan animals differ from coelenterate animals?
Answer:
Poriferan:
• Possess cellular organization.
• Have pores known as ostia covering their entire body.
• Lack tentacles.
• Possess an external skeleton.
• Have a water canal system to move water across their body.
Coelenterate:
• Possess tissue organization.
• Lack pores.
• Possess tentacles.
• No skeleton exists.
• Lack a canal system to move water.
In simple words: Poriferans (sponges) have simple cell groups, many body pores, no tentacles, and a water movement system. Coelenterates (like jellyfish) have more complex tissues, no pores, tentacles, and no water movement system.

Exam Tip: Focus on the fundamental differences in body organization (cellular vs. tissue level), specialized structures (pores/ostia vs. tentacles), and water circulation systems.

 

Question 15. How do annelid animals differ from arthropods?
Answer:
Annelids:
• Their body is segmented both outside and inside.
• They lack a chitin exoskeleton.
• They possess setae or parapodia for movement.
• Their coelomic cavity does not contain blood.
Arthropoda:
• Their body is segmented externally but without internal segments.
• They possess a chitinous exoskeleton.
• They possess jointed legs for movement.
• Their coelomic cavity contains blood.
In simple words: Annelids have bodies segmented both inside and out, no hard outer shell, and move with bristles or fleshy limbs. Arthropods have an outer shell of chitin, jointed legs, and only external segmentation.

Exam Tip: Highlight segmentation (internal vs. external), presence/absence of an exoskeleton, and specific locomotion structures (setae/parapodia vs. jointed legs).

 

Question 16. What are the differences between amphibians and reptiles?
Answer:
Amphibians:
• They can exist both on land and in water.
• They do not have scales on their body and possess slimy skin.
• They deposit eggs in water.
• Their eggs lack a tough outer layer.
Reptiles:
• Most are land-dwelling creatures.
• They possess dry scales on their body.
• They deposit their eggs mainly on land.
• Their eggs possess a tough covering to prevent dehydration.
In simple words: Amphibians live in water and on land, have moist skin without scales, and lay soft eggs in water. Reptiles mainly live on land, have dry scales, and lay tough, protective eggs on land.

Exam Tip: Focus on habitat (aquatic/terrestrial), skin characteristics (slimy/scales), and egg-laying environment/protection for distinguishing amphibians and reptiles.

 

Question 17. What are the differences between animals belonging to the Aves group and those in the mammalia group?
Answer:
Aves:
• They lack mammary glands to produce milk for their offspring.
• They are oviparous, meaning they lay eggs.
• Their front limbs are changed into wings covered by feathers.
• They possess a beak.
Mammalia:
• They possess mammary glands to produce milk for their offspring.
• They are viviparous, meaning they give birth to live young.
• Their body is covered with hair and contains sweat and oil glands.
• A beak is not present.
In simple words: Birds (Aves) lay eggs, have wings, and no milk glands. Mammals give birth to live young, have hair, milk glands, and no beak.

Exam Tip: Distinguish Aves and Mammalia by reproduction (oviparous vs. viviparous), presence of mammary glands, body covering (feathers vs. hair), and limb modification (wings).

 

In-Text Activities Solved

 

Activity 7.1

Answer: No, a desi cow is not similar to a Jersey cow. No, not all desi cows appear the same. Yes, we can recognize a Jersey cow among many desi cows that are not identical to each other. Our identification would rely on the length, height, body build, the shape and size of its horns, coat color and patterns, and the shape and size of its tail, among other features.
In simple words: A desi cow is different from a Jersey cow, and even desi cows are not all identical. We can tell a Jersey cow apart by looking at its size, body shape, horns, color, and tail.

Exam Tip: For descriptive tasks, list multiple distinguishing features, demonstrating a comprehensive understanding of observational differences.

 

Activity 7.2

Answer:
1. No, not all the seeds do not split into two almost equal halves.
2. Dicots possess tap roots, while monocots have fibrous roots.
3. Dicots show reticulate venation, whereas monocots display parallel venation.
4. Dicots exhibit pentamerous flowers, meaning their petals are in groups of 5 or multiples of 5. Monocots have trimerous flowers, meaning their petals are in groups of 3 or multiples of 3.
(i) In monocots, the coleoptile safeguards the plumule, and the coleorrhiza safeguards the radicle; however, no such protective structure is observed in the dicot embryo.
(ii) Dicots typically possess non-endospermous seeds, while monocots generally have endospermous seeds.
(iii) In dicots, the seed coat is distinct from the fruit, whereas in monocots like maize, wheat, etc., the seed coat is joined with the fruit wall.
In simple words: Not all seeds split perfectly. Dicots have tap roots and net-like leaf veins, with flower petals in fives. Monocots have fibrous roots and parallel leaf veins, with flower petals in threes. Also, monocots have protective coverings for their embryo parts, while dicots generally don't, and their seed coats are often fused to the fruit.

Exam Tip: For comparative questions about dicots and monocots, clearly list their distinguishing features regarding roots, venation, flower parts, and seed characteristics.

 

Activity 7.3

Answer: Students should collect common names of different plants and animals in their local language and other regional languages like Hindi, Kannada, and Tamil. This activity helps to comprehend the cultural and linguistic variety in naming organisms, emphasizing the significance of scientific names for global communication.
In simple words: For this activity, gather the common names of various plants and animals in your local language and other languages like Hindi, Kannada, and Tamil. This shows how different cultures name living things and why scientific names are important for everyone to understand.

Exam Tip: Activities often aim to foster inquiry and cross-cultural understanding. For such questions, explain the purpose of the activity and its educational value.

 

 

Activity 7.4

Answer: Students should list the scientific names corresponding to the common names provided in the table. This activity emphasizes the standardized naming system used in biology, which helps in avoiding confusion caused by different common names in various languages.
In simple words: For this activity, write down the scientific names for the animals and plants listed. This shows how scientific names give every living thing one clear name to avoid mix-ups from different local names.

Exam Tip: Understand the necessity of binomial nomenclature for global scientific communication, as common names vary significantly across regions and languages.

 

 

 

The scientific names are either Latin or made Latin-like. Therefore, the everyday names for plants and animals differ from their scientific names.

 

Question 1. What are the advantages of classifying organisms?
Answer: The advantages of classifying organisms are that:
1. Their identification and examination becomes simpler.
2. It offers a more organized structure to the huge amount of organism diversity present on Earth.
3. It assists in comprehending the interrelationships and evolutionary patterns among organisms.
4. It aids in anticipating the traits or characteristics of organisms based on the group they are part of.
In simple words: Classifying organisms makes it easier to identify and study them. It helps organize the many different living things on Earth, understand how they are related and evolved, and predict what new organisms in a group might be like.

Exam Tip: When listing advantages, aim for a comprehensive list that covers ease of study, organization, understanding relationships, and predictive power.

 

Question 2. How would you choose between two characteristics to be used for developing a hierarchy in classification?
Answer: The chosen characteristics should begin with the feature that creates the widest division. The subsequent characteristic selected should depend on the prior characteristic and division, in addition to having its own distinct features. This approach should continue for higher levels to construct a classification hierarchy. For example, the grouping of organisms into two main categories – prokaryotes and eukaryotes – establishes the foundation for further characteristics on which their classification relies.
In simple words: To classify organisms, start with the biggest difference first. Then, for each new step, pick a characteristic that builds on the last one and adds a new detail. Keep doing this to make a sorted list. For instance, first you divide by whether cells have a nucleus (prokaryote or eukaryote).

Exam Tip: Emphasize starting with fundamental, broad characteristics and progressively using more specific traits, ensuring each step builds logically on the previous division in the hierarchy.

 

Question 3. Explain the basis for grouping organisms into five kingdoms.
Answer: R.H. Whittaker categorized organisms into five kingdoms based on four primary factors:
(i) Cell structure: This distinguishes two groups, prokaryotes and eukaryotes, based on the absence or presence of a clear nuclear membrane.
(ii) Thallus organization: Organisms are grouped as unicellular (single-celled) or multicellular (many-celled) based on how many cells they are made of.
(iii) Mode of nutrition: Organisms are grouped as autotrophs (make their own food) or heterotrophs (rely on other organisms for food) depending on how they obtain sustenance.
(iv) Phylogenetic relationship: The evolutionary past of an organism is called its phylogeny. This factor groups organisms into simpler types with older traits and more complex types with newer, developed traits.
In simple words: Whittaker sorted organisms into five kingdoms using four main things: how their cells are built (with or without a nucleus), if they are one cell or many, how they get food (make it or eat it), and their family history or evolution.

Exam Tip: List all four criteria for Whittaker's Five Kingdom Classification (Cell structure, Thallus organization, Mode of nutrition, Phylogenetic relationship) and briefly explain each point.

 

Question 4. What are the major divisions in the Plantae? What is the basis for these divisions?
Answer: The Kingdom Plantae has the following main divisions:
(i) Thallophyta
(ii) Bryophyta
(iii) Pteridophyta
(iv) Gymnosperms
(v) Angiosperms
The basis for these divisions is:
(i) The presence or absence of clearly differentiated body parts/components. For example, Algae, which are members of Thallophyta, do not possess clearly differentiated components in their body.
(ii) The presence or absence of vascular tissues (that is, xylem and phloem). Bryophytes do not have vascular tissues.
(iii) The presence or absence of the capacity to produce seeds. Pteridophytes lack the capacity to produce seeds.
(iv) Whether seeds are enclosed within a fruit or not. Gymnosperms produce exposed seeds because their seeds are not covered by a fruit.
In simple words: The main plant groups are Thallophyta, Bryophyta, Pteridophyta, Gymnosperms, and Angiosperms. They are sorted by: if they have different body parts, if they have tubes to carry water (vascular tissues), if they can make seeds, and if their seeds are inside a fruit or exposed.

Exam Tip: List all five divisions of Plantae. For the basis of division, categorize the points by structural differentiation, vascular tissue, seed presence, and seed enclosure, providing an example for each.

 

Question 5. How are the criteria for deciding divisions in plants different from the criteria for deciding the subgroups among animals?
Answer: The standards for categorizing plant divisions differ from those for animal subgroups because animals do not display the features shown by plants. This is because of their distinct body structures and component organization. Plants are categorized based on body differentiation, vascular tissues, capacity to produce seeds, and whether seeds are covered by fruits. For animals, the criteria used include body organization into cells, tissues, and organs, embryonic layers, symmetry, metamerism, coelom, and the existence or non-existence of a notochord, among other factors.
In simple words: The ways we sort plants are different from how we sort animals because plants and animals have very different body plans. Plants are sorted by things like body parts, water tubes, and seeds. Animals are sorted by how their bodies are organized, their body layers, how symmetrical they are, and if they have a notochord.

Exam Tip: Contrast plant classification criteria (e.g., body differentiation, vascular tissue, seeds) with animal classification criteria (e.g., cell/tissue/organ organization, symmetry, coelom, notochord) to highlight their distinct evolutionary paths.

 

Question 6. Explain how animals in Vertebrata are classified into further subgroups.
Answer: Vertebrates are categorized into various groups based on their increasing complexity, beginning with organisms having simple body structures. The standards applied include:
(i) Type of skeleton present: The skeleton is composed of cartilage in cartilaginous fishes and bones in bony fishes (Pisces).
(ii) Type of respiration: Skin is moist to the touch, and breathing happens through gills in larvae, solely for Amphibians.
(iii) Presence of dry scales: The presence of dry scales on the body, as observed in Reptilia.
(iv) Beak, modified forelimbs, feathers, and egg-laying: The presence of a beak, forelimbs adapted into wings, covered by feathers, and an egg-laying group known as Aves.
(v) Mammary glands, hair, external ears, and live birth: The presence of mammary glands, hair on the body, external ears, and the capacity to give birth to live young, characteristic of Mammalia.
In simple words: Vertebrates are sorted into groups based on how complex they are, starting simple. Key things used to sort them are: what kind of skeleton they have (cartilage or bone), how they breathe (gills, skin), if they have dry scales, if they have beaks, wings, feathers, and lay eggs (birds), and if they have milk glands, hair, and give birth to live young (mammals).

Exam Tip: For Vertebrata subgroups, detail key evolutionary adaptations like skeletal type, respiratory mechanisms, skin coverings, specialized limbs (wings), and reproductive strategies (egg-laying/live birth, mammary glands).