Important Questions Class 12 Biology Chapter 1

Class 12 Biology Chapter 1 Important Questions and Answers – Reproduction in Organism

Extramarks experts have combined the Chapter 1 Class 12 Biology Important Questions, for students so that they can learn all the important questions with their answers and study well in their exams. Extramarks is one of the best learning platforms where class 12 students can completely rely on for study material and to get a better understanding of all the chapters..

Here, we have Class 12 Biology Chapter 1 Important Questions. Let’s go through  some of the important questions that will help students to learn about the CBSE board perspective and get an idea of how to crack the exam with the best possible results.

CBSE Biology Class 12 Chapter 1 Important Questions – Reproduction In Organisms

The Chapter 1 Class 12 Biology Important Questions offered here covers all the topics related to reproduction. Reproduction is the process through which creatures produce young ones that are identical to them. The process is crucial for the survival of species and the maintenance of environmental balance. Sexual and asexual reproduction are the two types of reproduction. Asexual reproduction is widespread in single-celled organisms, plants, and animals, and results in offspring that are genetically and physically identical. Sexual reproduction is the fusion of male and female gametes that results in offspring that are genetically unidentical from the parents.

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

Very Short Answer Questions(One Mark)

Q1. Why  are offsprings produced by asexual reproduction are referred to as clones?  

Ans: Offsprings produced by asexual reproduction are referred to as clones because the kids produced by the process of asexual reproduction are morphologically and genetically similar to the parent, so they are known as  clones.

Q2.Name the most invasive aquatic plant weed which is called Terror of Bengal.

Ans:The water hyacinth, also known as Eicchornia, is the plant that is considered to be the most invasive aquatic weed.

Q3. 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.

Q4. 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. Asexual reproduction results in offspring that are genetically similar, whereas  progeny produced by sexual reproduction exhibits genetic variation.

Q5.Which characteristic property of Bryophyllum is exploited by gardeners and farmers? The gardeners and farmers exploit this.

Ans:The plant species known as bryophyllum has unique traits in its adventitious buds. It generates adventitious buds from the plant’s leaf edges, which in turn generate new plants. The gardener uses this unique quality of Bryophyllum to propagate the plant commercially.

Q6.What represents the life span of an organism? 

Ans :The time from an organism’s birth until its natural death is considered the organism’s life span.

Q7.Which individuals can be termed as clones? 

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

Q8.How do the following organisms reproduce: Paramoecium and Penicillium? 

1. a) A parasitic organism, or paramecium, reproduces through binary fission. By using this method, organisms divide into two after duplicating their genetic material.
2. b) Penicillium is the kind of organism that uses unique asexual structures on its body known as conidia to reproduce.

 Q9.State the function of a vegetative propagule.

Ans:The structure of plants known as vegetative propagules is present in plants that have an asexual vegetative cycle and is capable of producing a totally new plant.

Q10. How will you grow a banana and a ginger plant? 

Ans: A rhizome, also referred to as a creeping rootstalk, is an underground plant stem that can give rise to a plant’s shoot and root systems. Rhizomes are so present in both ginger and bananas.

Q11. 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.

Q12.Rearrange the following events occurring during the sexual reproduction of flowering plants in the correct sequence: Embryogenesis, Fertilization, Pollination, Gametogenesis.

Ans- Pollination, Gametogenesis, Fertilisation, Embryogenesis

Q13.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.

Short Answer Questions (2 Marks)

Q1. Why do  higher organisms resort  to sexual reproduction despite its complexity? 

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

Q2. 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.

Q3. 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

Q4. 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 the 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.

Q5.Bryophytes and Pteridophytes produce a large number of male gametes but relatively very few female gametes. Why?

Ans: Male gametes need a medium (water) to reach egg/female gametes, which is the major reason why bryophytes and pteridophytes produce many male gametes but comparatively fewer female gametes. So there is a chance of male gametes getting lost in the water and not reaching female gametes.

 Q5.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

 Q6.Classify the Following Organisms as Monoecious and Dioecious: Marchantia, Chara, Cockroach, and Earthworm. 

Ans- Monoecious: Earthworm, Chara

Dioecious: Marchantia, Cockroach

Q7.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.

Q8.Why do hilly areas of Kerala, Karnataka, and Tamil Nadu transform into blue stretches that attract many tourists?

Ans:A plant called Strobilanthus kunthiana causes the hilly regions of Kerala, Karnataka, and Tamil Nadu to turn into blue stretches. This plant only blooms once every twelve years. The hilly regions of Kerala, Karnataka, and Tamil Nadu were turned into blue stretches by flowering in 2006.

Q9.What regulates the reproduction processes and the associated behavioural expressions in organisms?

Ans:The reproductive processes and associated behavioural expressions of various organisms are regulated by interactions between various types of hormones and environmental variables.

Q10.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.

There are three stages of sexual reproduction:

Pre- fertilisation

Fertilisation

Post-fertilization

Long Answer Questions (3 Marks)

Q1. Mention the site of zygote formation in the ovule of a flowering plant. What happens to sepals, petals, and stamens after fertilisation? 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 fertilisation 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, the ovule develops into seed and ovary into fruit.

Q2.Distinguish between gametogenesis and embryogenesis. 

Ans: The following are the differences between gametogenesis and embryogenesis:

Gametogenesis

The process of development of mature haploid gametes from the diploid or haploid precursor cells is known as gametogenesis.

Male and female gametes are formed in this process.

In the case of animals it takes place in the testes and ovaries. While in the plant’s case it takes place in antherdia and archegonia.

Embryogenesis

The process of formation and development of an embryo is known as embryogenesis.

Embryo development takes the place and forms zygote in this process.

In the case of animals it takes place in the female reproductive system and in terms of plants it takes place in the female gametophyte.

Q3.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.
•  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.

Q4.What happens during embryogenesis?

Ans: This is the process by which an animal or plant’s embryo develops. The process of embryonic development begins with the fertilisation of an egg cell by a sperm cell. Once fertilised, the ovum develops into a single diploid cell known as a zygote. 

Q5. 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:

i)It allows the propagation of a species.

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

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

Q6. In Which Type of Reproduction Does Reduction Division Occur?

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

Short Answer Questions For Class 12 Biology Chapter 1

Q1.Differentiate Between Estrous and Menstrual Cycles. 

Ans-

Oestrous Cycle

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

It lasts for a short time period.

No blood flow is involved.

Menstrual Cycle

Occurs in primates including monkeys, humans, etc.

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

The cycle involves blood flow.

Q2.List the Changes that Occur in a Flower After Fertilisation.

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

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

The ovule forms the seed.

The ovary is changed into a fruit.

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