NCERT Exemplar for Class 12 Biology Chapter 1

 

NCERT Exemplar for Class 12 Biology will aid in deepening the knowledge of students related to the topic of Reproduction In Organism. This provided exemplar by SimplyAcad allows students to cover all the areas and sections comprising the chapter 1 of the biology textbook. Our subject experts have provided different answer type questions such as very short or MCQs based, short and long answer type questions. It will benefit the students as they become more familiar with these dynamic patterns. Students can easily access this NCERT exemplar for class 12 biology in this article below to perform incredibly well in their upcoming 12th board examinations. Apart from these there are several NCERT exemplar for class 12 science of all the chapters provided in a detailed manner.

Access the NCERT Exemplar Class 12 Biology Chapter 1 Reproduction In Organism

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 has 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.

Solution:

Option (c) is the answer.

 

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.

Solution:

Option (a) is the answer.

 

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.

Solution:

Option (c) is the answer.

 

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

Solution:

Option (b) is the answer.

 

5. A multicellular, filamentous alga exhibits a type of sexual life cycle in which the meiotic division occurs after the formation of a 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

Solution:

Option (d) is the answer.

 

6. The male gametes of rice plants 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.

Solution:

Option (c) is the answer.

 

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 a 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

Solution:

Option (b) is the answer.

 

8. The statements given below describe certain features that are observed

in the pistil of flowers.

i. A pistil may produce more than one seed

ii. Each carpel may have more than one ovule

iii. Each carpel has only one ovule

iv. The pistil has 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

Solution:

Option (a) is the answer.

 

9. Which of the following situations correctly describes 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

Solution:

Option (b) is the answer.

 

10. The appearance of vegetative propagules from the nodes of plants such as

sugarcane and ginger are 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

Solution:

Option (b) is the answer.

 

11. Which of the following statements supports the view that an 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, iii and iv (d) ii, iii and iv

Solution:

Option (c) is the answer.

 

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. The greater amount of DNA is involved in sexual reproduction.

Solution:

Option (b) is the answer.

 

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 invertebratesSolution:

Option (c) is the answer.

 

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. The parental body is distributed among the offspring

d. They are microscopic

Solution:

Option (c) is the answer.

 

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

Solution:

Option (d) is the answer.

 

16. Identify the incorrect statement.

a. In asexual 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

Solution:

Option (b) is the answer.

 

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

Solution:

Option (b) is the answer.

 

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

Solution:

Option (a) is the answer.

 

VERY SHORT ANSWER TYPE QUESTIONS

1. Mention two inherent characteristics of Amoeba and yeast that enable them to reproduce asexually.

Solution:

a. Their structural organisation is simple.

b. Only single parent is involved, that is, they are single parental

 

2. Why do we refer to offspring formed by the asexual method of reproduction as clones?

Solution:

In the process of asexual reproduction, and only a single parent is involved so no genetic and morphological variation takes place so that we refer to offspring formed by the asexual method of reproduction as clones.

 

3. Although potato tuber is an underground part, it is considered as a stem. Give two reasons.

Solution:

They have leaf shoots arising from the nodes. The tuber has internodes.

 

4. Between an annual and a perennial plant, which one has a shorter juvenile phase? Give one reason.

Solution:

As the annual plant has a shorter life span than the perennial plants, its juvenile phase is also shorter than the perennial plants.

 

5. Rearrange the following events of sexual reproduction in the sequence in which they occur in a flowering plant: embryogenesis, fertilization, gametogenesis, and pollination.

Solution:

The sequence is as follows:

Pollination → Gametogenesis → Fertilization → Embryogenesis

 

6. The probability of fruit set in a self-pollinated bisexual flower of a plant is far greater than a dioecious plant. Explain.

Solution:

A bisexual flower has both male and female flowers in themselves, but in the dioecious plant, they are unisexual they need an agent for the transfer of pollen grain, were in bisexual, the transfer of pollen is easier.

 

7. Is the presence of a large number of chromosomes in an organism a hindrance to sexual reproduction? Justify your answer by giving suitable reasons.

Solution:

The basis of sexual reproduction is the generation of haploid gamete only so, the presence of a greater number of gametes does not affect the reproduction. For example, Fern plant has 1260 chromosomes but still, it reproduces sexually.

 

8. Is there a relationship between the size of an organism and its life span? Give two examples in support of your answer.

Solution:

There is no relationship between the size of an organism and its life span. For example, the Mango tree and the banyan tree have the same size but they differ in their life span.

 

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.

Solution:

‘A’ is a chasmogamous flower. Self-pollination or cross-pollination occurs, while ‘B’ is a cleistogamous flower which is self-pollinated.

 

10. Give reasons as to why cell division cannot be a type of reproduction in multicellular organisms.

Solution:

In unicellular organisms, cell division takes place because each parent body forms a daughter cell whereas in multicellular not because no differentiation occurs.

 

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

Solution:

 

12. Why do gametes produced in large numbers in organisms exhibit external fertilisation?

Solution:

Gametes produced in large numbers in organisms exhibit external fertilization because gametes are released in an open environment. This causes them to expose constantly to predators and thus reduces the number of gametes.

 

13. Which of the following are monoecious and dioecious organisms?

a. Earthworm ______________

b. Chara ______________

c. Marchantia ______________

d. Cockroach _____________

Solution:

a. Earthworm “monoecious”

b. Chara “monoecious ”

c. Marchantia ”dioecious”

d. Cockroach ”dioecious”

 

14. Match the organisms given in Column-’A’ with the vegetative propagules

given in column ‘B’

Col. A i. Bryophyllum ii. Agave iii. Potato iv. Water hyacinth	Col. B a) offset b) eyes c) leaf buds d) bulbils

Solution:

i is c

ii is d

iii is b

iv is a

 

15. What do the following parts of a flower develop into after fertilization?

a. Ovary ______________

b. Ovules ______________

Solution:

a. Ovary “Fruit”

b. Ovules” Seeds”

SHORT ANSWER TYPE QUESTIONS: NCERT Exemplar Class 12 Biology Chapter 1 Reproduction In Organism

1. In haploid organisms that undergo sexual reproduction, name the stage in the life cycle when meiosis occurs. Give reasons for your answer.

Solution:

These haploid cells only show meiotic division, not meiosis, when the formation of zygote takes place as the zygote is the only diploid cell in their life cycle.

2. The number of taxa exhibiting asexual reproduction is drastically reduced in higher plants (angiosperms) and higher animals (vertebrates) as compared with lower groups of plants and animals. Analyse the possible reasons for this situation.

Solution:

The higher plants and higher animals have a complex structural organization that allows them to use the sexual mode of reproduction and then produce genetically variable offspring. They have more superior survival and adaptation capability than those which are produced asexually.

3. Honeybees produce their young ones only by sexual reproduction. Despite this, in a colony of bees, we find both haploid and diploid individuals. Name the haploid and diploid individuals in the colony and analyse the reasons behind their formation.

Solution:

A honeybee hive has three kinds of members which are

1. Diploid Queen which is fertile females

2. Worker bees are sterile females.

3. Drones which are haploid males.

Both gametes combine to produce offspring which can either produce diploid or haploid males.

4. With which type of reproduction do we associate the reduction division? Analyze the reasons for it.

Solution:

Meiosis is known as reduction division because Meiosis is involved in gamete production, which occurs in sexual reproduction. The gametes will have half the number of chromosomes as their nature is haploid.

5. Is it possible to consider vegetative propagation observed in certain plants like Bryophyllum, water hyacinth, ginger etc., as a type of asexual reproduction? Give two/three reasons.

Solution:

1. It involves only one parent.

2. No gamete formation takes place.

3. The offspring has the same genetic composition as the parent.

6. ‘Fertilization is not an obligatory event for fruit production in certain plants’. Explain the statement.

Solution:

‘Fertilization is not an obligatory event for fruit production in certain plants’ because, in some plants unfertilized egg grows into an embryo, this process is known as parthenogenesis.

7. In a developing embryo, analyse the consequences if cell divisions are not followed by cell differentiation.

Solution:

If in a developing embryo, cell divisions are not followed by cell differentiation, the embryo would not grow into an organism as the cells would not differentiate to forms tissues and then organs and would remain as a mass.

8. List the changes observed in an angiosperm flower after pollination and fertilization.

Solution:

1. Ovary 2. Ovary wall 3. Ovule 4. Outer integument 5. Inner integument 6. Secondary nucleus 7. Egg 8. Synergids and antipodals 9. Hilum, Funicle and micropyle	Fruit Pericarp Seed Testa Tegmen Endosperm Zygote Degenerate Show no changes

9. Suggest a possible explanation of why the seeds in a pea pod are arranged in a row, whereas those in tomato are scattered in the juicy pulp.

Solution:

Pea and tomato plants show different types of placentation, which describes the type of arrangement of ovules inside the ovary. The pea plant shows Marginal Placentation which means that the ovules are arranged into two rows along the rigid ventricular suture, whereas the tomato plant shows Axileplacentation, which means the ovules are arranged along the central axis of the ovary.

10. Draw the sketches of a zoospore and a conidium. Mention two dissimilarities between them and at least one feature common to both structures.

Solution:

– Zoospore is endogenously formed inside the sporangium and flagellated

– Conidium is formed inside conidiophores exogenously and is non-flagellated.

11. Justify the statement ‘Vegetative reproduction is also a type of asexual reproduction’.

Solution:

Vegetative reproduction is also a type of asexual reproduction because it involves only one parent. In this reproduction, the clone formation takes place the young one will be similar to that of the parent.

Gamete formation does not take place and the offspring will have the same genetic composition as that of the parent.

LONG ANSWER TYPE QUESTIONS: NCERT Exemplar Class 12 Biology Chapter 1 Reproduction In Organism

1. Enumerate the differences between asexual and sexual reproduction. Describe the types of asexual reproduction exhibited by unicellular organisms.

Solution:

Asexual reproduction	Sexual reproduction
1. Only one parent is involved 2. Gamete formation does not take place 3. Male gamete fusion does not take place 4. Offspring will be an exact copy of their parents. 5. Genetic variation does not take place.	Male and female parents are involved Male and female gamete formation takes place Male and female gamete fusion takes place Offsprings are varied genetically and physically from parents The genetic variation takes place

Asexual reproduction is different kinds they are:

1. Binary Fission: The parent cell divides its DNA into two, these DNA then incorporates into two identical daughter cells produced from the parent body, example: Amoeba

2. Budding: A small nod or growth on the surface of the parent body derives nutrition from the parent, then detaches and grow into another being. Example: Hydra, Yeast.

3. Fragmentation: The parent body divides into many fragments, and every fragment develops into offspring. Example: starfish

4. Parthenogenesis: The unfertilized eggs develop into an embryo to form an invertebrate like a fish, frog and other reptiles.

2. Do all the gametes formed from a parent organism have the same genetic composition (identical DNA copies of the parental genome)? Analyse the situation with the background of gametogenesis and provide or give a suitable explanation.

Solution:

In sexual reproduction, the fusion of male and female gamete takes place. Therefore the gametes formed from a parent organism do not have the same genetic composition. Both female and male gametes will have different genetic makeup and their recombination leads to the formation of the gamete that has different DNA composition.

3. Although sexual reproduction is a long drawn, energy-intensive complex form of reproduction, many groups of organisms in Kingdom Animalia and Plantae prefer this mode of reproduction. Give at least three reasons for this.

Solution:

1. Genetically varied offspring due to the recombination of the qualitatively different male and female DNA.

2. Due to the recombination of DNA, genetical variations are seen in the offspring.

3. This type of reproduction is useful as due to genetical variation, the adaptation and survival compatibility increases

4. Differentiate between (a) oestrus and menstrual cycles; (b) ovipary and vivipary. Cite an example for each type

Solution:

OESTRUS CYCLE	MENSTRUAL CYCLE
1. Takes place in non-primates 2. The endometrium lining is reabsorbed 3. Blood does not flow down 4. Copulation happens in the heat season only Example: Cow	1. Takes place in primates only 2. The endometrium lining of the uterus breaks down and passes down 3. Blood flow takes place 4. Copulation takes place in any season. Example: Human beings

OVIPAROUS	VIVIPAROUS
1. They lay eggs and do not give birth to young ones 2. The egg may be fertilized or unfertilized 3. The young ones are protected inside a hard-calcareous shell 4. Example: Fish, reptiles	1. They give birth to the young ones only 2. The egg undergoes internal fertilization 3. The fertilized egg develops inside the female body 4. Example: Mammals

5. Rose plants produce large, attractive bisexual flowers, but they seldom produce fruits. On the other hand, a tomato plant produces plenty of fruits though they have small flowers. Analyse the reasons for the failure of fruit formation in roses.

Both these plants – rose and tomato – both selected by human beings for different characteristics, the rose for its flower and the tomato for its fruit. Roses, being vegetative propagated, do not need to produce seeds.

Solution:

Rose plants produce large, attractive bisexual flowers but they seldom produce fruits. On the other hand, a tomato plant produces plenty of fruits though they have small flowers. Because

1. The pollens produced by the rose plants may not be viable, which means they may not have the compatibility to germinate; hence fertilization does not take place.

2. Pollen-pistil interaction may not take place

3. As the rose plants are hybrid the mitotic division in them may be abnormal, which may produce non-viable gametes.

4. A barrier is present in the pollen tube where the male gametes are restricted from reaching the ovule.

NCERT Exemplar For Class 12 Science

Students must practise these additional questions for their own benefits, the ncert exemplar are curated by the best subject-matter experts to boost their knowledge on the presented topic. Students can easily access the ncert exemplar for class 12 science by visiting our website SimplyAcad and solve all the questions listed to secure maximum marks.

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