NCERT Exemplar: Reproduction in Organisms - 1 (Old NCERT) | Biology Class 12 - NEET PDF Download

MULTIPLE CHOICE QUESTIONS 

Q.1. A few statements describing certain features of reproduction are given below
i. Gametic fusion takes place
ii. Transfer of genetic material takes place
iii. Reduction division takes place
iv. Progeny have some resemblance with parents 
Select the options that are true for both asexual and sexual reproduction from the options given below
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (ii) and (iv)
(d) (i) and (iii)
Ans. (c)
Solution.
Gametic fusion and reduction division take place only in case of sexual reproduction. Hence, (ii) and (iv) are correct statements.

Q.2. The term ‘clone’ cannot be applied to offspring formed by sexual reproduction because:
(a) Offspring do not possess exact copies of parental DNA
(b) DNA of only one parent is copied and passed on to the offspring
(c) Offspring are formed at different times
(d) DNA of parent and offspring are completely different.
Ans. (a)
Solution.
Gametogenesis takes place through meiosis and crossing over takes place during meiosis. Crossing over is responsible for some alteration in genotype. Moreover, fertilization results in gene pools from two different individuals and thus zygote has a somewhat different genotype than both the presents. Hence, the term clone cannot be applied to offspring formed by sexual reproduction.

Q.3. Asexual method of reproduction by binary fission is common to which of the following?
i. Some eukaryotes
ii. All eukaryotes
iii. Some prokaryotes
iv. All prokaryotes
Choose the correct option from the following
(a) i and ii
(b) ii and iii
(c) i and iii
(d) iii and iv
Ans. (c)
Solution.
Various methods of asexual reproduction are seen in prokaryotes, like binary fission, multiple fission, spore formation, etc. In eukaryotes; many methods of asexual reproduction as well as sexual reproduction are seen.

Q.4. A few statements with regard to sexual reproduction are given below
i. Sexual reproduction does not always require two individuals
ii. Sexual reproduction generally involves gametic fusion
iii. Meiosis never occurs during sexual reproduction
iv. External fertilisation is a rule during sexual reproduction
Choose the correct statements from the options below
(a) i and iv
(b) i and ii
(c) ii and iii
(d) i and iv
Ans. (b)
Solution.
In some case, both the sexes are present on the some individual and some of those cases, both the gametes from the same individual are involved in fertilization, e.g. selfpollination in many flowering plants. Fusion of gametes, i.e., fertilization is an important step in sexual reproduction. Hence, (i) and (ii) are correct.

Q. 5. A multicellular, filamentous alga exhibits a type of sexual life cycle in which the meiotic division occurs after the formation of zygote. The adult filament of this alga has
(a) Haploid vegetative cells and diploid gametangia
(b) Diploid vegetative cells and diploid gametangia
(c) Diploid vegetative cells and haploid gametangia
(d) Haploid vegetative cells and haploid gametangia
Ans. (d)
Solution.
Many algae show haplontic life cycle. In this case, the dominant phase is free living gametophyte. Sporophytic generation is represented by single-called zygote. Meiosis results in formation of haploid spores, e.g. Spirogyra and Chlamydomonas.

Q.6. The male gametes of rice plant have 12 chromosomes in their nucleus.
The chromosome number in the female gamete, zygote and the cells of the seedling will be, respectively,
(a) 12, 24, 12
(b) 24, 12, 12
(c) 12, 24, 24
(d) 24, 12, 24
Ans. (c)
Solution.
Gametes have haploid number of chromosomes, zygote and plant have diploid number of chromosomes.

Q.7. Given below are a few statements related to external fertilization. Choose the correct statements.
i. The male and female gametes are formed and released simultaneously
ii. Only a few gametes are released into the medium
iii. Water is the medium in a majority of organisms exhibiting external fertilization
iv. Offspring formed as a result of external fertilization have better chance of survival than those formed inside an organism
(a) iii and iv
(b) i and iii
(c) ii and iv
(d) i and iv
Ans. (b)
Solution.
Release of both the gametes simultaneously is necessary to ensure fertilization.
The male gametes need some medium through which they can travel up to the female gamete. Water is the medium for most the cases; while air is a medium in some cases.

Q.8. The statements given below describe certain features that are observed in the pistil of flowers.
i. Pistil may produce more than one seed
ii. Each carpel may have more than one ovule
iii. Each carpel has only one ovule
iv. Pistil have only one carpel Choose the statements that are true from the options below: 
(a) i and ii
(b) i and iii
(c) ii and iv
(d) iii and iv
Ans: (a)
Solution.

• Pistil may have many carpels (multicapillary pistil like Papaver)
• Each carpel may have more than one ovule (like Watermelon,.Papaya etc.)

Q.9. Which of the following situations correctly describe the similarity between an angiosperm egg and a human egg?
i. Eggs of both are formed only once in a lifetime
ii. Both the angiosperm egg and human egg are stationary
iii. Both the angiosperm egg and human egg are mobile
iv. Syngamy in both results in the formation of zygote Choose the correct answer from the options given below
(a) ii and iv
(b) iv only
(c) iii and iv
(d) i and iv
Ans. (b)
Solution.
In angiosperms, eggs are formed several times in the lifetime, hence option (i) is incorrect. 

In humans, eggs travel from ovary to fallopian tubes; so, option (ii) is incorrect.
In angiosperms, eggs are stationary and hence option (iii) is incorrect.

Q.10. Appearance of vegetative propagules from the nodes of plants such as sugarcane and ginger is mainly because:
(a) Nodes are shorter than internodes
(b) Nodes have meristematic cells
(c) Nodes are located near the soil
(d) Nodes have non-photosynthetic cells
Ans. (b)
Solution.
Presence of meristematic cells gives the ability of vegetative propagation.

Q.11. Which of the following statements, support the view that elaborate sexual reproductive process appeared much later in the organic evolution.
i. Lower groups of organisms have simpler body design
ii. Asexual reproduction is common in lower groups
iii. Asexual reproduction is common in higher groups of organisms
iv. The high incidence of sexual reproduction in angiosperms and vertebrates Choose the correct answer from the options given below:
(a) i, ii and iii;
(b) i, iii and iv
(c) i, ii and iv
(d) ii, iii and iv
Ans. (c)
Solution.
Asexual reproduction is not common in higher groups of organisms; especially in animals. Hence, option (iii) is incorrect. Rest or the options are correct.

Q.12. Offspring formed by sexual reproduction exhibit more variation than those formed by Asexual reproduction because
a. Sexual reproduction is a lengthy process
b. Gametes of parents have qualitatively different genetic composition
c. Genetic material comes from parents of two different species
d. Greater amount of DNA is involved in sexual reproduction
Ans. (b)
Solution.
Fertilization during sexual reproduction results in gene pools from two different individuals and thus zygote has a somewhat different genotype than both the parents and show more variation.

Q.13. Choose the correct statement from amongst the following
(a) Dioecious (hermaphrodite) organisms are seen only in animals
(b) Dioecious organisms are seen only in plants
(c) Dioecious organisms are seen in both plants and animals
(d) Dioecious organisms are seen only in vertebrates
Ans. (c)
Solution.
Many flowering plants are dioecious. Pheretima is an example of dioecious animal.

Q.14. There is no natural death in single celled organisms like Amoeba and bacteria because:
(a) They cannot reproduce sexually
(b) They reproduce by binary fission
(c) Parental body is distributed among the offspring
(d) They are microscopic
Ans. (c)
Solution.
Binary fission results in culmination of parental generation and beginning of the next generation but the mother cell does not die in the process rather it gets divided into two daughter cells.

Q.15. There are various types of reproduction. The type of reproduction adopted by an organism depends on:
(a) The habitat and morphology of the organism
(b) Morphology of the organism
(c) Morphology and physiology of the organism
(d) The organism’s habitat, physiology and genetic makeup
Ans. (d)
Solution.
The organism’s habitat, its internal physiology and several other factors (genetic make up) are collectively responsible for how it reproduces. When offspring is produced by a single parent with or without the involvement of gamete formation, the reproduction is asexual.

Q.16. Identify the incorrect statement.
(a) In a sexual reproduction, the offspring produced are morphologically and genetically identical to the parent
(b) Zoospores are sexual reproductive structures
(c) In asexual reproduction, a single parent produces offspring with or without the formation of gametes
(d) Conidia are asexual structures in Penicillium
Ans. (b)

Q.17. Which of the following is a post-fertilisation event in flowering plants?
(a) Transfer of pollen grains
(b) Embryo development
(c) Formation of flower
(d) Formation of pollen grains
Ans. (b)
Solution.
The sequence is as follows:
formation of flower → formation of pollen grains → transfer of pollen grains → fertilization → Embryo development.

Q.18. The number of chromosomes in the shoot tip cells of a maize plant is 20. The number of chromosomes in the microspore mother cells of the same plant shall be
(a) 20
(b) 10
(c) 40
(d) 15
Ans. (a)
Solution.
Microspore mother cell has same ploidy as the vegetative parts.

VERY SHORT ANSWER TYPE QUESTIONS

Q.1. Mention two inherent characteristics of Amoeba and yeast that enable them to reproduce asexually.
Ans. Amoeba and yeast are able to reproduce asexually because of following reasons:
(a) They are unicellular organisms
(b) They have simple organization

Q.2. Why do we refer to offspring formed by asexual method of reproduction as clones?
Ans. In asexual reproduction, a single parent is involved in reproduction and the process involves mitosis only. Due to this, variation is not possible in offspring and they are clones of their parent.

Q.3. Although potato tuber is an underground part, it is considered as a stem. Give two reasons.
Ans. Following features on potato tuber are signs of it being a stem:
(a) Presence of nodes (eyes)
(b) Presence of scaly leaves

Q.4. Between an annual and a perennial plant, which one has a shorter juvenile phase? Give one reason.
Ans. Annual plants have shorter juvenile phase compare to perennial plans. Moreover, it also depends on number of flowering seasons in a given year. Some perennial plants Produce flower Only once in a year. Some others may produce flowers once in 50 year or even 100 years. This is not the situation in annual plants.

Q.5. Rearrange the following events of sexual reproduction in the sequence in which they occur in a flowering plant: embryogenesis, fertilisation,  gametogenesis, pollination.
Ans. Gametogenesis → Pollination → Fertilisation → Embryogenesis

Q.6. The probability of fruit set in a self-pollinated bisexual flower of a plant is far greater than a dioecious plant. Explain.
Ans. A self-pollinated plant does not have to depend on agents of pollination. But a dioecious plant has to depend on the agents of pollination for carrying out sexual reproduction. In certain circumstances, the agents of pollination may not be available because of various external factors. For example; use of high level of pesticides has reduced the number of pollinating insects. This is playing havoc with sexual reproduction in many flowering plants.
So, the probability of fruit set in a self-pollinated bisexual flowers of a plant is far greater than a dioecious plant.

Q.7. Is the presence of large number of chromosomes in an organism a hindrance to sexual reproduction? Justify your answer by giving suitable reasons.
Ans. The presence of large number of chromosomes in an organism is not a hindrance to sexual reproduction because number of chromosomes has no role in deciding a particular mode of reproduction. For example; there are 8 chromosomes in a somatic cell of fruit fly, while there are 380 chromosomes in a somatic cell of butterfly but both of them produce sexually.

Q.8. Is there a relationship between the size of an organism and its life span? Give two examples in support of your answer.
Ans. There is no relationship between the size of an organism and its life span. For example; both mango and peepal tree are similar in size but a mango tree has a much shorter life span compared to a peepal tree. A tortoise is much smaller than an elephant yet the tortoise lives more than hundred years.

Q.9. In the figure given below the plant bears two different types of flowers marked ‘A’ and ‘B’. Identify the types of flowers and state the type of pollination that will occur in them

Ans. ‘A’ shows chasmogamous flowers with exposed anthers and stigma and cross pollination will happen in them. ‘B’ shows flowers which do not open at all. These are bisexual flowers and self-pollination will happen in them. On the other hand, agents of pollination can easily work in flower ‘A’ as its anthers and stigma are exposed.

Q.10. Give reasons as to why cell division cannot be a type of reproduction in multicellular organisms.
Ans. Most of the multicellular organisms have complex organization. Especially the animals show tissue level and organ system level organization. For a single cell, it is not possible to produce different tissues just by undergoing mitosis. Hence, cell division cannot be a type of reproduction in multicellular organisms.

Q.11. In the figure given below, mark the ovule and pericarp.
Ans.


Q.12. Why do gametes produced in large numbers in organisms exhibit external fertilisation?
Ans. In case of external fertilization, gametes are at the mercy of surrounding. Gametes can get blown off by wind, washed away by water or eaten by predators. So, most of the gametes perish before fertilization. To ensure the survival of the species, it is necessary to produce as many gametes as possible so that at least some of them would be able to carry out fertilization. Hence, organisms which exhibit fertilization produce a large number of gametes.

Q.13. Which of the followings are monoecious and dioecious organisms.
a. Earthworm ______
b. Chara ______
c. Marchantia ______
d. Cockroach ______
Ans.
(a) Monoecious Animal
(b) Monoecious Plant
(c) Dioecious Plant
(d) Dioecious Animals

Q.14. Match the organisms given in Column-’A’ with the vegetative propagules given in column ‘B’.

 Ans.
(i) → (c)
(ii) → (d)
(iii) → (b)
(iv) → (a)

Q.15. What do the following parts of a flower develop into after fertilisation?
a. Ovary ______
b. Ovules ______
Ans.
(a) Fruits
(b) Seeds