Important Questions for Class 12 Biology

Important Questions about Organisms’ Reproduction System’ Type of Long Response

Question 1: Specify what you mean by “define.”(i) the developmental stage, (ii) the adolescent phase, (iii) the senescence phase,

Answers: (i)Phase of juvenile.

Phase of juvenile. The juvenile phase of an organism’s life is the period of growth that occurs before the organism begins reproducing sexually and reaches a certain level of maturity. The reproductive phase follows immediately after.

(ii) The period of reproduction

This is the stage of reproduction. The reproductive phase is defined as the period of active reproductive behavior during which the organisms undergo significant morphological and physiological changes. Senescence occurs immediately after this phase.

(iii) There is also a senescence phase.

Senescence is a stage of life. The senescence phase is defined as the time period between the end of the reproductive phase and the onset of concomitant changes in the body, such as a slowing of metabolism. It is followed by the end of life.

Question 2: Make a distinction between asexual reproduction and sexual reproduction. Why is vegetative reproduction considered to be a type of asexual reproduction in addition to sexual reproduction?

Answer: The distinctions between asexual reproduction and sexual reproduction are discussed.

Asexual reproduction is a type of reproduction that does not involve sexual contact.

Sexual Reproduction is a term that refers to the act of reproducing sexually.

There is only one cell or one parent involved in the process.

This procedure involves the union of two cells or gametes that are either from the same or different parents.

A single cell or a bud can serve as a reproductive unit, or the entire body of the parent can serve as a reproductive unit.

The gamete, which is a unicellular and haploid reproductive unit, is the reproductive unit.

Third, the offspring are genetically identical to their parents.

The children are different from their parents.

Only mitotic division occurs during this process.

Both meiosis and mitosis take place at the same time.

There is no development of sex organs.

It is necessary for the development of sex organs.

There is no evolutionary significance to this.

It contributes to the introduction of variation, and as a result, it has evolutionary significance.

Because it does not involve meiotic division and there is no formation and fusion of gametes, vegetative reproduction is also considered to be an asexual mode of reproduction.

Question 3: What is the process by which an encysted Amoeba reproduces when favorable conditions are restored? (CBSE Sample Paper for 2019-20) (English)

Answer: encysted Amoeba undergoes multiple fissions:

Amoeba withdraws its pseudopodia and secretes a cyst wall around itself to protect itself from infection. Encencystation is the term used to describe this phenomenon.

Several fissions occur in the division of the amoeba.

An excessive number of pseudo-conidiospores are produced by this pathogenic organism.

The rupture of the cyst wall.

The spores are liberated and settle down on suitable substrates, where they develop into amoebae and reproduce. This is referred to as sporulation in some circles.

Question 4: Asexual reproduction has both advantages and disadvantages, which should be discussed.

Answer:  Asexual reproduction has a number of advantages, including the following:

It is a straightforward mitotic division in a single-parent situation, and it can result in a large number of offspring.

When children are born through asexual means, they are genetically identical to their parents.

It aids in the dispersal of offspring to far-flung areas of the world.

Asexual reproduction has a number of disadvantages.

The young ones that are thus produced do not have a great deal of ability to adapt quickly to the environmental changes that occur in rapid succession.

There is no genetic recombination, and as a result, there is no variation.

Question 5:.Discuss the benefits and drawbacks of sexual reproduction in this context.

Answer: The following are some advantages of sexual reproduction:

Genetic recombination, interaction, and other processes take place, resulting in variations in the offspring and, in turn, supplying raw materials for evolution.

The offspring are more comfortable and quick to adapt to changes in environmental conditions, which increases their chances of survival in the long run.

Disadvantages associated with sexual reproduction In most cases, two parents of opposing sexes are required to raise their children (except in hermaphrodite).

Evolution Important Extra Questions Short Answer Type

Question 1: How do vestigial organs differ from normal organs? Give specific examples.

Answer: Vestigial organs are organs in an organism that are no longer functional but are still functional in related animals and were functional in the organism’s ancestors. It is estimated that the human body contains 90 vestigial organs, the majority of which are the coccyx (tail bone), nictitating membrane (3rd eyelid), caecum and vermiform appendix; canines; wisdom teeth; body hair; auricular muscles; and mammary glands in males, among other things. The presence of vestigial organs can also be found in other animals, such as splint bones in the horse, hind limbs, and pelvic girdles in the python, wings and feathers in flightless birds, and so forth.

Question 2: Explain the significance of vestigial organs in your own words.

Answer: Vestigial organs have a significant historical significance. Organic evolution holds that these vestigial organs were functional in the ancestral forms, but that they have become non-functional as a result of changes in their function, and that they may eventually become extinct. As a result, the presence of vestigial organs is compelling evidence of organic evolution, and Lamarck’s theory of use and disuse of organs lends support to this conclusion.

Question 3:What exactly are fossils?

Answer: Fossils. Fossils are the remains or imprints of living organisms that existed in the distant past and have been preserved. The burial of dead organisms is a necessary step in the formation of fossils. Over the dead organisms, layer after layer of sediment is piled on top of them. On this basis, the oldest fossils are found in the deepest layers of the earth’s surface, whereas the fossils of more recent origin are found in the upper layers of the earth’s surface. As a result, by studying the fossil record preserved in the various layers of the earth, ranging from the deepest to the most superficial strata, it is possible to reconstruct the storey of life in its proper historical sequence.

Question 4: What is the significance of Archaeopteryx being referred to as a “connecting link” between reptiles and birds? Or Where does Archaeopteryx fit into the study of organic evolution, and what does it mean for us today?

Answer: The significance of the Archaeopteryx as a connecting link The fossil forms that represent the characteristics of two distinct groups of living animals are referred to as “missing links” in the scientific community. Archaeopteryx, a fossil bird from the Cretaceous period, provides the best example of a connecting link. It was the size of a crow in terms of size. Archaeopteryx is unmistakably a bird, as evidenced by the presence of feathers and a beak. However, it resembles reptiles in that it has a long tail, teeth-filled jaws, claws on the forefingers, and a keelless sternum. As a result, it represents a transitional stage between reptiles and birds, represented by an Archaeopteryx-like intermediate form.