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Our NCERT Solutions for Class 12 Biology is a great resource for students preparing for boards or competitive exams, such as the NEET. These Biology Class 12 Solutions are made by expert faculties, keeping the latest curriculum in mind. Besides helping students with understanding the concepts of Biology, these solutions are also helpful in writing accurate answers that are vital to score full marks in examinations. On this page, we have given the Class 12 Biology Chapter 1: Reproduction in Organisms Solutions.
NCERT Solutions for Class 12 Biology Chapter 1
Reproduction in Organisms Solutions
Q1) Why is reproduction essential for organisms?
Answer) Reproduction is a fundamental feature of all living organisms. It is a biological process through which living organisms produce offspring’s similar to them. Reproduction ensures the continuance of various species on the Earth. In the absence of reproduction, the species will not be able to exist for a long time and may soon get extinct.
Q2) Which mode of reproduction is better: asexual or sexual? Why?
Answer) Sexual reproduction is better than asexual reproduction because it produces offsprings that are genetically unique from the parents. It also means that the offspring will be more resilient and be able to survive better than either parent due to genetic variation.
Q3) Why is the offspring formed by asexual reproduction referred to as clone?
Answer) A clone is a group of morphologically and genetically identical individuals. In the process of asexual reproduction, only one parent is involved and there is no fusion of the male and the female gamete. As a result, the offsprings so produced are morphologically and genetically similar to their parents and are thus, called clones.
Q4) Offspring formed due to sexual reproduction have better chances of survival. Why? Is this statement always true?
Answer) Sexual reproduction is said to occur when two gametes fuse. This leads to the production of the offspring that are genetic variants of the parents and therefore, are able to survive better.
However, the organisms produced by sexual reproduction do not always survive more than those produced by asexual reproduction. Sometimes, the organisms produced by asexual reproduction survive better than those produced by sexual reproduction. Also, it is a fairly quick process and consumes less energy and time.
Q5) How does the progeny formed from asexual reproduction differ from those formed by sexual reproduction?
|Progeny formed from asexual reproduction||Progeny formed from sexual reproduction|
|Asexual reproduction does not involve the fusion of the male and the female gamete. Organisms undergoing this kind of reproduction produce offspring’s that are morphologically and genetically identical to them.||Sexual reproduction involves the fusion of the male and the female gamete of two individuals, typically one of each sex. Organisms undergoing this kind of reproduction produce offspring’s that are not identical to them.|
|Offsprings thus produced do not show variations and are called clones.||Offspring’s thus produced show variations from each other and their parents.|
Q6) Distinguish between asexual and sexual reproduction. Why is vegetative reproduction also considered as a type of asexual reproduction?
Answer) Differences between sexual and asexual reproduction are mentioned below:
|Sexual reproduction||Asexual reproduction|
|It takes place by the fusion of male and female gametes.||In this, the organism arises from a single organism.|
|It requires two (usually) different individuals.||It requires only one individual.|
|It is a slow process.||It is faster compared to sexual reproduction.|
|The offsprings produced are not identical to the parents.||The offsprings produced are identical to the parents and are known as clones.|
|Most animals reproduce sexually. Both sexual and asexual modes of reproduction are found in plants.||Asexual modes of reproduction are common in organisms having simple organizations such as algae and fungi.|
Q7) What is vegetative propagation? Give two suitable examples.
Answer) Vegetative propagation is a common form of asexual reproduction observed in plants. In this, a fragment of a plant is used to grow another plant. Many plants reproduce naturally as well as artificially by vegetative propagation and the offsprings produced are genetically identical.
Examples of vegetative reproduction are: ginger, garlic
(a) Juvenile phase
(b) Reproductive phase
(c) Senescent phase
Answer a) It is the period of growth in an individual organism after its birth and before it reaches reproductive maturity.
Answer b) It is the phase in which an organism can reproduce sexually. In males, it lasts until death, but in females it lasts until the age of 50.
Answer c) It is the period when an organism grows old and loses the ability to reproduce.
Q9) Higher organisms have resorted to sexual reproduction in spite of its complexity. Why?
Answer) Higher organisms undergo sexual reproduction despite its complex nature because the organisms are produced by the fusion of two different gametes and therefore show genetic variations. Due to these variations, they are well adapted to different environmental factors, and hence usually have higher rates of survival.
Q10) Explain why meiosis and gametogenesis are always interlinked?
Answer) Meiosis is a process of reductional division in which the amount of genetic material is reduced. Gametogenesis is the process of the formation of gametes. Gametes produced by organisms are haploids (containing only one set of chromosomes), while the body of an organism is diploid. Therefore, for producing haploid gametes (gametogenesis), the germ cells of an organism undergo meiosis. During the process, the meiocytes of an organism undergo two successive nuclear and cell divisions with a single cycle of DNA replication to form the haploid gametes.
Q11) Identify each part in a flowering plant and write whether it is haploid (n) or diploid (2n).
- Male gamete
- Ovary – Diploid (2n)
- Anther – Diploid (2n)
- Egg – Haploid (n)
- Pollen – Haploid (n)
- Male gamete – Haploid (n)
- Zygote – Diploid (2n)
Q12) Define external fertilization. Mention its disadvantages.
Answer) External fertilization is a mode of reproduction characterized by the fertilization of male and female gametes outside the body of the organisms. External fertilization is observed in amphibians such as frogs and toads.
Disadvantages of external fertilization:
In external fertilization, eggs have less chances of fertilization. This can lead to the wastage of a large number of eggs produced during the process.
Further, there is an absence of proper parental care to the offspring, which results in a low rate of survival in the progenies.
Q13) Differentiate between a zoospore and a zygote.
Answer) Here are the main differences between a zoospore and a zygote:
|These are formed inside the zoosporangium.||These are formed by the fusion of male and female gametes.|
|It is an asexual reproductive structure.||It is formed as a result of sexual reproduction.|
|A zoospore is a motile asexual spore that utilizes the flagella for movement.||A zygote is a non-motile diploid cell formed as a result of fertilization.|
|Can be haploid or diploid.||Diploid.|
|It is found in algae, fungi and protozoans.||Found in higher organisms.|
Q14) Differentiate between gametogenesis from embryogenesis.
Answer) Here are the main differences between gametogenesis from embryogenesis:
|It is the process of formation of male and female gametes.||It is the process of formation and development of an embryo.|
|Both meiosis and mitosis occur during the process.||Just mitosis occurs during the process.|
|Oogenesis and spermatogenesis are the two processes of gametogenesis.||Embryogenesis leads to organogenesis.|
|Occurs before fertilization.||Occurs after fertilization.|
|Formation of haploid gametes.||Formation of diploid cells of the embryo.|
Q15) Describe the post-fertilization changes in a flower.
Answer) Fertilization is the process of the fusion of the male and the female gamete to form a diploid zygote. After fertilization, the zygote divides several times to form an embryo. The fertilized ovule forms a seed. The seed contains an embryo, enclosed in a protective covering, called the seed coat. As the seed grows further, other floral parts wither and fall off. This leads to the growth of the ovary, which enlarges and ripens to become a fruit with a thick wall called the pericarp.
Q16) What is a bisexual flower? Collect five bisexual flowers from your neighborhood and with the help of your teacher find out their common and scientific names.
Answer) The flowers that contain both female and male reproductive structures are considered as a bisexual flower. The androecium is the male reproductive structure, while the female reproductive structure is gynoecium.
These are the most common examples of bisexual flowers:
- Solanum lycopersicum (Tomato)
- Tulipa (Tulip)
- Helianthus (Sunflower)
- Brassica (Mustard)
- Narcissus (Daffodil)
Q17) Examine a few flowers of any cucurbit plant and try to identify the staminate and pistillate flowers. Do you know any other plant that bears unisexual flowers?
Answer) Flowers that bear stamens are called staminate flowers while the flowers that bear pistil are known as pistillate flowers. Cucurbit plants bear unisexual flowers, i.e., both the male and female reproductive structures are on the same plant.
That’s it. These were the solutions of NCERT Class 12 Biology Chapter 1 – Reproduction in Organisms. Our team hopes that you have found these solutions helpful for you. If you have any doubt related to this chapter then feel free to comment your doubts below. Our team will try their best to help you with your doubts.