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Important Questions for CBSE Class 12 Biology Chapter 1 - Reproduction in Organism 2023-24

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MVSAT 2024

CBSE Class 12 Biology Chapter-1 Important Questions - Free PDF Download

Important questions for Class 12 Biology chapter 1 are prepared to keep all the important topics from the chapter in mind. Experts at Vedantu have put together the important questions for class 12 biology chapter 1, reproduction in organisms from the latest NCERT books. These questions can help the students achieve a better understanding of the topic, which is reproduction. Reproduction in organisms class 12 important questions have been provided to help students understand the important topics of the chapter and get an insight into the type of questions that can be asked in the examination. 

 

Let us begin by understanding the topic- Reproduction in organisms and then refer to chapter 1 Biology class 12 important questions.

 

Download CBSE Class 12 Biology Important Questions 2023-24 PDF

Also, check CBSE Class 12 Biology Important Questions for other chapters:

Competitive Exams after 12th Science

Study Important Questions for Class 12 Biology Chapter 1 Reproduction In Organisms

Very Short Answer Questions(One Mark)

1. Offsprings produced by asexual reproduction are referred to as clones. Why? 

Ans: Offsprings produced by asexual reproduction are known to be clones because offsprings produced by the method of asexual reproduction are morphologically and genetically similar to the parent. 


2. Name the most invasive aquatic plant weed which is called Terror of Bengal.

Ans: The plant which is known to be the most invasive aquatic plant weed is called Water hyacinth. It is also known as Eicchornia.


3. How does Zygote usually differ from Zoospore in terms of ploidy?

Ans: A zygote is a diploid whereas a zoospore is a haploid therefore they differ in their ploidy.


4. Mention the main difference between the offspring produced by asexual reproduction and progeny produced by sexual reproduction. 

Ans: The offspring produced by different means of reproduction varies mostly in the genetic constitution. Offspring which are produced by asexual reproduction are genetically similar, on the other hand, progeny produced by sexual reproduction exhibits genetic variation. 


5. Which characteristic property of Bryophyllum is exploited by gardeners and farmers? The gardeners and farmers exploit this.

Ans: Bryophyllum is the type of plant which shows special characteristics of adventitious buds in it. It gives rise to the adventitious buds from the edges of leaves of the plant which eventually give rise to new plants. This special property of Bryophyllum is exploited by the gardener for the commercial propagation of the plant. 


6. What represents the life span of an organism? 

Ans:  The life span of an organism is defined as the period from the birth of the organism to the natural death of an organism.

7. Which individuals can be termed as clones? 

Ans: The clone is the term given to individuals who are morphologically and genetically identical i.e similar to each other.


8. How do the following organisms reproduce: Paramoecium and Penicillium? 

Ans: a) Paramoecium is that type of organism that reproduces by the process of binary fission. In this method, organisms duplicate their genetic material and then divide into two.

b) Penicillium is that type of organism that reproduces with the help of special asexual structures present in their body called conidia. 


9. State the function of a vegetative propagule.

Ans: The vegetative propagules are the structure of plants that are found in plants that have an asexual vegetative cycle and these are capable of giving rise to a completely new plant.


10. How will you grow a banana and a ginger plant? 

Ans: Rhizome, commonly known as creeping rootstalk, is defined as a horizontal underground plant stem that can produce the shoot and root systems of a plant. Therefore, rhizomes are found in both bananas and ginger.


Short Answer Questions (2 Marks)

1. Higher organisms have resorted to sexual reproduction despite its complexity. Why? 

Ans: Higher organisms have resorted to sexual replication even after having such complexity because offspring of sexual reproduction have variations in their genes which help them in survival. It helps organisms to adapt to the environment easily.


2. Tapeworms possess both male and female reproductive orgAns: What is the name given to such an organism? Give two more examples of such organisms. 

Ans: The organism which possesses both male and female reproductive organs is known as Hermaphrodite.

Examples of such organisms are Earthworm and Leech. 


3. Study the relationship between the first two words and suggest a suitable word for fourth place. 

(a) Male flower : Stamens :: Female Flower : ............................. 

Ans: Carpel


(b) Birds: oviparous:: Primates: ............................. 

Ans: Viviparous


(c) Chlamydomonas: Zoosporbananascan produces:: Penicillium: ............................. 

Ans: Conidia


(d) Ginger : Rhizome :: Agave : ............................. 

Ans: Bulbil


4. Bryophytes and Pteridophytes produce a large number of male gametes but relatively very few female gametes. Why? 

Ans: The main reason behind Bryophytes and Pteridophytes producing many male gametes but relatively very few female gametes is that male gametes need medium (water) to reach egg/female gametes. So there is a chance of male gametes getting lost in the water and not reaching female gametes.


5. Enlist the significance of reproduction. 

Ans: Significance of the reproduction is as follows:

  1. One of the main importance of reproduction to occur is to preserve the continuity of the species. 

  2. The process of reproduction guarantees that a species does not disappear from Earth.

  3. This process is very important, as it helps maintain stability in the ecosystem and the continuation of life on earth. 

  4. If reproduction does not take place, all the species would have become extinct.


6. Why do hilly areas of Kerala, Karnataka, and Tamil Nadu transform into blue stretches that attract many tourists? 

Ans: The hilly areas of Kerala, Karnataka, and Tamil Nadu transform into blue stretches because of one of the plants which are known as Strobilanthus kunthiana. This plant flowers only once in every 12 years. Flowering in 2006 resulted in the transformation of the hilly tracts of Kerala, Karnataka, and Tamil Nadu into blue stretches.


7. Define ‘oestrus’ and ‘menstrual cycles. 

Ans: The oestrus cycle and menstrual cycle can be defined as:

Oestrus cycle: During this cycle, the female is fertile and sexually receptive, sometimes referred to as “being in heat” due to the related rise in body temperature.

Menstrual cycle: The menstrual cycle occurs in the females of the primates. This is a more complex process and has phases that depend upon the hormonal changes occurring in the body.

For example, the oestrous cycle in the cows is for 21 days whereas the menstrual cycle in humans is for 28 days.


8. What regulates the reproduction processes and the associated behavioural expressions in organisms? 

Ans: Interaction between different types of hormones and certain environmental factors helps to regulate the reproductive processes and the associated behavioural expressions of different organisms. 


9. Mention the different stages of sexual reproduction. 

Ans: Sexual reproduction is that category of reproduction method that includes the fusion of gametes including sperm or egg cells with a single pair of chromosomes (haploid) that mixes with some other to form an organism with pairs of chromosomes that is diploid.

Three levels of sexual reproduction:

  1. Pre- fertilization

  2. Fertilization

  3. Post-fertilization


Long Answer Questions (3 Marks)

1. Mention the site of zygote formation in the ovule of a flowering plant. What happens to sepals, petals, and stamens after fertilization? State the fate of zygote, ovule, and ovary in these plants. 

Ans: The embryo sac is known to be the site of zygote formation. The embryo sac is the site where zygote formation takes place. The embryo sac or female gametophyte is an oval shape present inside the ovule of flowering plants. An embryo sac formation takes place after the division of haploid megaspore nuclei. It possesses haploid nuclei and 6 haploid cells which now no longer have cell walls.

  • Once fertilization takes place, the sepals, petals, and stamens of the flower wither and fall off. 

  • The pistil, however, stays connected to the plant. The zygote then develops into the new part which is known as an embryo and the ovules change into the seed. 

  • The ovary develops into the fruit which develops a thick wail referred to as pericarp that is shielding in function.

  • In the end,  Ovule develops into seed and ovary into fruit.


 2. Distinguish between gametogenesis and embryogenesis. 

Ans:  The difference between gametogenesis and embryogenesis are as follows:-

Gametogenesis 

Embryogenesis

It is the process of development of mature haploid gametes from the diploid or haploid precursor cells.

It is defined as the process of formation and development of an embryo.

In this process, male and female gametes are formed.

In this process, embryo development will take place and form the zygote.

It takes place in the testis and ovaries in the case of animals. In the case of plants,  it takes place in the antheridia and archegonia.

In animals, this process takes place in the female reproductive system, on the other side in plants in the female gametophyte.


3. Fill the blank spaces a, b, c, and d given in the following table. 

Organism 

Organ

Gamete

a.

Testes

Spermatozoa

Human female

b. 

Ovum

Plant (Angiosperm)

Pollen grains

Plant (pteridophytes)

antheridium

d


Ans:

Organism 

Organ

Gamete

a. Human Male

testes

Spermatozoa

Human female

b. Ovary

Ovum

Plant (Angiosperm)

c. Anther

Pollen grains

Plant (pteridophytes)

antheridium

d. Antherozoid


4. What are heterogametes? What do we call these gametes individually? 

Ans: The conjugating gametes that are exclusive of their form, length, shape or sexes, etc. are known as heterogametes.

  • The gametes of an organism are the reproductive or intercourse cells.  The gametes that are just like every other are known as homogametic. Heterogametes vary from every different in form and length.

  • Ex. The Spermatozoa which is known as a male gamete is spiral, small in length, and motile.

  • The Ovum which is known as a female gamete is oval, huge in length, and immovable.

  • Hence, they're known as heterogametes.

  • In such types of organisms, the male gamete is called the antherozoid or sperm and the female gamete is called the egg or ovum.


5. Why is syngamy a major event in sexual reproduction? 

Ans: The fusion of the male and female gametes at some stage in fertilization is known as syngamy. Syngamy guarantees the continuity of species in a sexually reproducing organism and this is what every individual wants i.e to continue their generation. In this process, a fusion of egg nucleus with make gamete resulting in the formation of diploid zygote or embryo.


6. What happens during embryogenesis? 

Ans: Embryogenesis- This process is the development of the embryo of an animal or plant. Embryonic development is the process that starts with the fertilization of an egg cell by a sperm cell. Once it is fertilized, the ovum will now become a single diploid cell known as a zygote.


7. Give any three differences between asexual and sexual reproduction.

Ans: The difference between asexual and sexual are as follows:-

Asexual Reproduction

Sexual Reproduction

There is the involvement of a single individual.

Two sexually active but distinct individuals are involved.

Formation of gametes does not take place.

Formation of gametes takes place.

Syngamy and zygote formation does not occur.

Syngamy and zygote formation occurs.


8. Enlist the changes that occur post-fertilization in plants. 

Ans: The various post-fertilization changes as observed in plants are as follows –

  • The sepal, petal, and stamen of the flower will wither and fall off. In the end, the only pistil remains attached to the plant. 

  • The ovules will develop into the seed.

  • The zygote will develop into the embryo.

  • The ovary will develop into the fruit.


9. (a) Distinguish between asexual and sexual reproduction. Why is vegetative reproduction also considered a type of asexual reproduction? 

Ans: (a)  The difference between asexual and sexual reproduction are as follows:-

Asexual Reproduction 

Sexual Reproduction

It is Uniparental.

It is Biparental. 

Gametes are not involved in this type of method.

Gametes are involved in this type of method.

The only mitotic division takes place here.

Both meiosis and mitosis will take place. Meiosis at the time of gamete formation and mitosis after fertilization

Offspring are genetically similar to the parent.

Offspring are different from parents.


Vegetative propagation is known as the process which takes place when new individuals arise from the vegetative part of the parent and have characteristics similar to that of the parent plant. 


(b) Which is a better mode of reproduction: Sexual or Asexual? Why?

Ans: Sexual reproduction helps in introducing variations in offspring and has evolutionary significance. It helps offspring to adjust according to the changes in the environment. It produces better offspring due to the combination of the characters.


CBSE Biology Class 12 Chapter 1 Reproduction In Organisms Important Questions

The important question of chapter 1 Biology class 12 provided here covers all the topics related to reproduction. Reproduction is a process that allows organisms to produce young ones that are identical to them. The process is integral for the continuation of species and maintaining a balance in the ecosystem. Reproduction can be classified into two types- sexual and asexual. Asexual reproduction is commonly observed in single-celled organisms, plants, and animals that give rise to genetically and morphologically identical off-springs. Sexual reproduction refers to the fusion of male and female gametes, which produces an unidentical offspring to the parents. 

The following Biology class 12 chapter 1 important questions can be referred to for preparing for 1 mark questions for the exam-


1. What Does the Term Vegetative Propagule Mean?

Ans- The vegetative structures of a plant that can give rise to a new plant are referred to as vegetative propagules. 


2. Name the Different Stages Associated with Sexual Reproduction.

Ans- Sexual reproduction can be divided into the following three stages-

Pre-fertilization events

Fertilization

Post-fertilization events


3. Rearrange the Following Events Occurring During the Sexual Reproduction of Flowering Plants in the Correct Sequence: Embryogenesis, Fertilization, Pollination, Gametogenesis.

Ans- Pollination, Gametogenesis, Fertilization, Embryogenesis


4. Explain Why Potato Tubers are Considered to be a Stem?

Ans- Even though a potato tuber is an underground part, it is considered to be a stem because it has nodes and internodes. The buds present over these nodes can form plantlets.


5. What Do Ovaries and Ovules of the Flowers Change into Post-Fertilization?

Ans- The ovary changes into the fruit while the ovule grows into a seed. 


6. What Do You Infer From the Term Clone?

Ans- Individuals that can be considered to be morphologically and genetically similar are referred to as clones.


7. Which One has a Shorter Juvenile Period- Annual or Perennial Plants, and Why?

Ans- Annual plants have a shorter juvenile period since their life cycle has to be completed within a year. 


8. Is There a Correlation Between the Size and the Life Span of an Organism?

Ans- No relationship exists between the size and the life span of an organism. This can be seen from a crow and a parrot which have the same size but vary significantly in life span. Crows live for 15 years whereas a parrot can live up to 140 years.


9. List the Various Types of Asexual Reproduction.

Ans- Binary fission, budding, sporogenesis, fragmentation, vegetative propagation.


10. What is the Main Difference Between Off-Springs Produced as a Result of Asexual and Sexual Reproduction?

Ans- Asexual reproduction results in the formation of genetically identical individuals, whereas sexual reproduction allows genetic variation to occur within the off-springs produced.   


Biology Chapter 1 Class 12 Important Questions for 2 Marks Questions are Provided Below-

1. Why Do Higher Organisms Perform Sexual Reproduction?

Ans- The reason why higher organisms have resorted to sexual reproduction- 

Variation

Gene pool

Better parental care

Vigour and vitality


2. Classify the Following Organisms as Monoecious and Dioecious: Marchantia, Chara, Cockroach, and Earthworm. 

Ans- Monoecious: Earthworm, Chara

         Dioecious: Marchantia, Cockroach


3. What Will Happen if Cell Differentiation Does not Follow Cell Division in an Embryo?

Ans- Cell division involves an increase in the number of cells, whereas cell differentiation refers to the transformation of the cell mass into specialized tissues and organs. If cell differentiation doesn’t occur after cell division, it will only remain a mass of cells and will not develop into an embryo.


4. Can Fruits be Produced Without the Fertilization Event in Some Plants?

Ans- Certain fruits such as grapes, pomegranate can develop from unfertilized ovaries. This type of fruit is called parthenocarpic fruits. In these plants, the ovule does not change into a seed, but the flower is provided with a growth hormone that results in fruit formation without fertilization. 


5. How Do Zoospores and Conidia Differ? Also, Mention a Similarity Between the Two.

Ans-

Zoospore

Conidium

Formed within a sporangium

Formed on the tip of conidiophores

Flagellated

Non-flagellated

Both of them aid in asexual reproduction in plants. 


6. Explain the Significance of Reproduction.

Ans- Reproduction is a process that allows organisms to continue their species, generation after generation. The significance of reproduction is that:

It allows the propagation of a species.

It is responsible for maintaining a balance in the ecosystem and sustaining life on this planet.

It provides an opportunity for genetic variation to occur, which leads to the evolution of new species.


7. In Which Type of Reproduction Does Reduction Division Occur?

Ans- Reduction division, also known as meiosis, occurs during sexual reproduction. The germ cells produced are diploid, and meiosis reduces the number to half. 


8. Where Does Syngamy Take Place in Reptiles and Amphibians?

Ans- In amphibians, syngamy occurs in water (external fertilization) whereas, in reptiles, it occurs within the body of the female organism (internal fertilization).


9. What Adaptations Do Animals With External Fertilization Show?

Ans- Both the sexes have to show synchrony, i.e. they have to release the gametes simultaneously. They have to release a large number of gametes to improve the chances of fertilization to occur.

These important questions for class 12 biology chapter 1 cover a vast number of topics related to reproduction. These involve the types and significance of reproduction, gametes, and their formation, estrous and menstrual cycle, etc. 


Short Answer Questions For Class 12 Biology Chapter 1

Vedantu provides you with the most important question of chapter 1 biology class 12 to help you properly understand how reproduction works in various types of organisms. These questions will help you revise the whole chapter conveniently.

Reproduction in organisms class 12 important questions that you can expect as 3 marks questions in the exam are given below. 

1.  List the Differences Between Gametogenesis and Embryogenesis.

Ans- 

Gametogenesis

Embryogenesis

It refers to the formation of gametes.

It refers to the formation of an embryo.

The result is haploid gametes.

Results in a diploid embryo.

Meiotic cell division occurs.

Mitotic cell division takes place. 


2. Explain the Significance of Syngamy in Sexual Reproduction.

Ans- Syngamy or fertilization is an important component of sexual reproduction in organisms. It is the fusion of the male and female gametes and results in a diploid zygote formation. This process is crucial for the exchange of genetic information and the production of variation in the offspring.


3. Differentiate Between Estrous and Menstrual Cycles. 

Ans- 

Oestrous Cycle

Menstrual Cycle

Occurs in non-primates like dogs, cows, etc.

Occurs in primates including monkeys, humans, etc.

It lasts for a short time period.

It includes various phases called the menstrual phase, proliferative phase, and secretory phase.

No blood flow is involved.

The cycle involves blood flow.

The endometrium gets reabsorbed after breaking.

The broken endometrium layer has to be shed off. 


3. List the Changes that Occur in a Flower After Fertilization.

Ans- The following changes take place inside a flower after fertilization:

Inside the ovule, a zygote is formed which further changes into an embryo.

The ovule forms the seed. 

The ovary is changed into the fruit.

The wall of the ovary forms a protective layer known as the pericarp.


4. Rose Plants Do Not Produce Fruits Even After the Presence of Large Flowers. Explain Why.

Ans- Rose plants do not bear fruits because:

The absence of viable pollen is the reason why fertilization does not take place. 

The ovules and eggs that are produced are non-functional.

These plants are self-incompatible.

They are sterile and reproduce vegetatively. 

These important questions of chapter 1 Biology class 12 cover all the important topics related to the chapter. They can help students prepare the topic well and score more marks in the examination. It is important to go through these questions carefully to understand the topic better and get an idea about the pattern of questions you can expect. 

Students should go through the Biology class 12 Chapter 1 important questions to understand the type of questions that can be asked in the examination. These questions can be saved for later and revised anytime to improve the student’s performance.


Important Related Links for CBSE Class 12 Biology

FAQs on Important Questions for CBSE Class 12 Biology Chapter 1 - Reproduction in Organism 2023-24

1. Which website caters to a well-curated set of important questions for Class 12 Biology Chapter 1 - Reproduction in Organisms? 

Vedantu provides a well-curated set of important questions for Class 12 Biology Chapter 1 Reproduction in Organisms. These questions are solved by subject matter experts at Vedantu. The online learning platform is known to cater to such thorough researched study materials to help students in exam preparations. At Vedantu, you can find important questions on the chapter to facilitate students with extra questions that can be asked in the exam. As these questions are included keeping the current academic curriculum in mind, these are really helpful to score well in the paper.

2. Why must students practice important questions for Class 12 Biology Chapter 1 Reproduction in Organisms?

Chapter 1 Reproduction in Organisms is an important chapter of Class 12 Biology CBSE syllabus. Solving extra questions for the chapter is really helpful during exams as it allows students to have a better understanding of the chapter. It also makes them aware of all types of questions that can be asked in the exam. The important questions are selected by experts to cover all the important topics of the chapters. E-learning sites like Vedantu provide the free PDF of important questions for Class 12 Biology Chapter 1 as well as other chapters which can be utilized at the time of revision. These are proven helpful in boosting students’ confidence while appearing for the board exam.

3. What are some of the important questions for Class 12 Biology Chapter 1?

Following are some of the important questions for Class 12 Biology Chapter 1:

  • Offsprings produced by asexual reproduction are referred to as clones. Why?

  • Name the most invasive aquatic plant weed which is called the Terror of Bengal.

  • How does zygote usually differ from Zoospore in terms of ploidy?

  • Which characteristic property of Bryophyllum is exploited by gardeners and farmers?

For more important questions, students can refer to important questions for the chapter on Vedantu’s site.

4. Why do living organisms need to reproduce?

Each organism can live for a certain period of time. Hence, organisms need to reproduce to continue the survival of their kind. The only way by which a species can continue to survive is by reproduction. It is a necessary process by which any living being maintains the continuity of its genes. An organism’s characteristics are heavily dependent on how it brings its offspring to the world. It is compulsory for Biology students to learn the reproduction process in order to understand how life sustains.

5. What do you understand by reproduction according to NCERT Solutions for Chapter 1 of Class 12 Biology?

Reproduction is a biological process where the living organism gives birth to the offspring, which has the similarity of the living organism giving birth. This offspring grows, gets mature and further gives birth to its own offspring. Reproduction is the continuous cycle of birth, growth and death and helps in the continuity of the species from generation to generation.

6. Name the important concepts discussed in NCERT Solutions for Class 12 Biology Chapter 1.

The topics in Class 12 Chapter 1 Reproduction are; 

  • Topic 1 Characteristic features of all organisms for continuation of species. 

  • Topic 2 Modes of Reproduction – asexual and sexual reproduction.

  • Topic 3 Asexual reproduction. 

  • Topic 4  Binary fission. 

  • Topic 5 Sporulation. 

  • Topic 6  Budding. 

  • Topic 7 Gemmule formation. 

  • Topic 8 Fragmentation. 

  • Topic 9 Vegetative propagation in plants.

These topics have to be studied and understood correctly to ace the exam. 

7. Sexual reproduction is the better way of reproduction. Give reasons?

Sexual reproduction is considered a better way of reproduction because the DNA of the two individuals is combined and forms a new variant. This is formed by the fusion of male and female gametes. Hence, the offspring produced can sustain the environmental changes. One more important reason is that the survival of the species is more significant compared to the other methods of reproduction.

8. What do you understand about clones?

The offspring formed by the asexual reproduction where only a single parent is involved is known as clones. This is a word used to describe genetically identical groups. This can be mainly seen in prokaryotic organisms and some eukaryotic single-celled and multicelled organisms. A detailed explanation of the chapter can be found in Vedantu’s NCERT Solution in a very organized way helping the students to have a better understanding.

9. What kind of reproduction is involved in the eyes of potato and leaf buds of Bryophyllum?

The process of reproduction in both cases is vegetative reproduction, which is also asexual reproduction. The new plants are obtained from the vegetative parts of a plant. Like the eyes of a potato, the surface of the potato that looks like an eye when buried gives rise to a new plant. Similarly, the Bryophyllum plant has many buds in the edges and when the leaves break, the shoots grow into a tiny new plant when they come in contact with the moist soil.