CBSE Class 12 Biology HOTs Reproduction In Organisms

Chapter-1 REPRODUCTION IN ORGANISMS

ONE MARK QUESTIONS:

1. Some organisms reproduce to produce genetically similar individuals.

What is the type of reproduction do they follow? Why are the individuals genetically similar?

2. How is gemma cup and gemmules differ from each other?

3. How is a nodal segment in sugarcane helpful as a reproductive unit?

4. How is vegetative propagation related to the following plants?

6. Do haploid organisms have meiosis in their lifecycle? If yes, state when does it occur?

7. What is common among earthworm, leech and sponge? Hint: with regard to reproductive organs.

8. Why do plants like bryophytes and pteridophytes produce a large number of male gametes?

9. Flowering varies from plant to plant. Give 2 examples in support of this statement.

10. Fertilization results in the production of zygote. Zygote is called as a vital link. Why is it called so?

11. If a branch “dasheri mango” is grafted on a tree producing “desi mangoes” what type of mangoes will be borne on grafted branch& other branches of the plant?

12. Most sugarcane varieties cultivated today are aneuploids and are sterile. But they grow and perform extremely well. Sterility in sugarcane is not of any disadvantage. Why?

13. Why do organisms like algae and fungi which normally adopt asexual reproduction switch over to sexual method of reproduction just before the onset of adverse conditions?

14. In a culture there is a mixture of haploid and diploid cells. It must be because ofa) Generative cells b) Vegetative cells c) another wall d) pollen cells.

TWO MARKS QUESTIONS:

1. Fill in the missing columns:

COLUMN A       COLUMN B

Penicillium                   A

Hydra                         B

C                        Gemmules

D                           Bulbils

2. Give the chromosome number in the gametes of the following, if the number of chromosomes in their meiocytes is as follows:

i.) Dog-78 ii) Rice – 24 iii) Housefly – 12 iv) Butterfly -380

i) Identify the given plants.

ii) How are they different from each other with regard to reproductive organs they possess.

4. Reptiles and frogs are oviparous animals; yet they differ in certain aspects of reproduction. Bring out the differences and mention which of the two animals has more advantage. Give one reason.

5. Name a plant where vegetative propagation occurs from reproductive organ. What is the special name of the reproductive part of the plant?

6. In non-primate mammals like cows, sheep, rats, deer etc, the cyclical changes that occur during reproduction are called oestrus cycle whereas in primates it is called as menstrual cycle. How can we distinguish between them?

Ans:

7. Do you agree with the statement only asexual reproduction can give rise to individuals resembling their parent? Support your answer with an example.

Ans: Parthenogenesis/ Rotifers, honeybees-unfertilized eggs-develop into adults.

8. Categorise the following plants based on the floral characteristics: Hibiscus, Cucumber, Papaya, Guava.

9. Sexual reproduction involves fertilization and the formation of embryo. What are the critical events needed for the successful reproduction process.

THREE MARKS QUESTIONS:

1. In a pond ecosystem you may find the plant with purple flowers that spread very fast to cover the entire pond within a short span of time. How does it spread? How does it harm the aquatic body?

2. Can we consider simple cell division as a method of reproduction? What will you call this kind of reproduction? Give two examples in support of your answer.

3. Complete the flowchart with reference to the reproduction of flower.

FIVE MARKS QUESTIONS:

1. Study the following diagram and answer the questions given below:

i. What does S and P denote?

ii. Where do they develop from?

iii. What is the term given to the point of attachment of the ovules in the fruit?

iv. What is the ploidy of embryo and the tissues in the ovary?

v. What is the function of fruit apart from storage of materials?

2. Fertilization leads to the formation of embryo.

i. Give the technical term for the development of embryo.

ii. What are the events that occur during embryo development?

iii. The development of zygote depends on two factors. What are they?

iv. How will you categorise animals based on the development of zygote inside or outside the female body?

v. How does zygote in fungi and algae overcome dessication?

REPRODUCTION IN ORGANISMS

1) No two individuals, especially in mammals (except monozygotic twins) look alike. What distinguishes them from the rest? 1

2) A plant was introduced in India because of its beautiful flowers & shape of leaves. It propagates vegetatively at a phenomenal rate and spread all over the water bodies and has become a threat. Which plant is being referred to? 1

3) A few plants exhibit unusual flowering phenomena which flowers once in their life time and die. Suggest an evidence of the same from monocotyledon.1

4) Identify A and B Label (1) and (2) in the given figure 1

5) The Nilgiris belt form the large blue stretches in the hilly areas of Kerala, Karnataka, & Tamilnadu and attracted a large number of tourists. What reason do you attribute to this phenomenal change of nature once in 12 years? 1

6) Why estrous cycle is not seen in humans? 1

7) All papaya and date palm plants produce flowers yet only few papaya and date palm seen to produce fruit. What could be the possible reason for the rest not producing them? 1

8) Often the number of male gametes produced in an organism is in large number as compared to female. Why has nature taken up this developmental disparity? 1

9) This figure shows fruit containing seed inside. Label S & P shown in fig. 1

10) In nature for both plants & animals, hormones are responsible for transitions between the three phases of reproduction. Which 3 phases are being referred to here?1

 

2 marks

 

11) Label A and B and write the type of the vegetative propagule. 2