Botany: Solved Previous Year’s Question Paper for NCERT/ CBSE  Class 12th Botany Paper Code (HSEIIRKN15—-6418-X) 

Botany: Solved Previous Year’s Question Paper for NCERT/ CBSE  Class 12th Botany Paper Code (HSEIIRKN15—-6418-X) 

 (Long Answer Type Questions) 

Question: Define cross-pollination. Name the contrivances that favour it and describe any two of them. 

Ans: The transfer of pollen from one flower to the stigma of another flower of the same species is known as cross-pollination. It is crucial to the process of many plants producing seeds. Wind, water, insects, and birds are artificial means that promote cross-pollination.

1) Insects: One of the most significant agents of cross-pollination is insects. As they feed, insects move pollen from one flower’s anthers to another’s stigma, allowing fertilisation to take place. They are drawn to flowers because of the nectar and pollen they produce.

2) Wind: Cross-pollination is helped by the wind, which is also crucial. Numerous plants produce tiny, airy pollen grains that can easily be carried by the wind from one flower to another. Because of this, there is a greater possibility that the pollen will successfully fertilise other flowers, even if they are far away.

 (Short Answer Type Questions) 

Question: Why did Mendel select garden peas for his experiments? 

Ans: Garden peas were chosen by Mendel to study because of their rapid reproduction, clearly observable qualities, and vast range of physical variety. Studies may be conducted with more accuracy because these characteristics are also simple to control. Furthermore, because peas self-fertilize, it was simple to research the impact of cross-pollination and the expression of characteristics in the progeny.

Question: Define tissue culture. Name any three applications of tissue culture. 

Ans: A technique used in laboratories to grow and preserve cells and tissues in a controlled environment is tissue culture. On a solid surface, like a Petri dish, and in a liquid media, like a cell culture medium, is how it is often carried out. The following are three uses for tissue culture: 1. Plant tissue culture: This method is used to develop plants with features like disease resistance, quick growth, or increased production. Animal cells are grown in cultures to understand how they develop and grow in a controlled setting. 3. Tissue culture is used to study the causes and spread of diseases, such as cancer, as well as to discover new therapies and cures.

Question: Name the various interactions in a biotic community and describe any one of them. 

Ans: 1. Predation 2. Competition 3. Symbiosis 4. Mutualism 5. Parasitism 6. Amensalism 7. Commensalism

1. Predation: In this interaction, one species (the predator) hunts and eats another species (the prey). This relationship is crucial to the functioning of the food chain since it influences the community’s structure and aids in controlling population numbers.

Question: Suggest any three measures for controlling pollution or our lakes 

Ans: 1. Put severe restrictions in place for wastewater disposal into lakes.

2. Raise awareness of the significance of clean lakes in society.

3. Increase funds for projects to restore and clean up lakes.

4. Construct treatment facilities and other pollution-control measures.

 5. Put optimum management methods for farming and other land-based industries into action.

6. Use less fertiliser and other chemicals close to rivers and lakes.

(Very Short Answer Type Questions) 

Question: The following very short answer type questions of 2 marks, each may be answered in a few words or a few sentences or as may be required. 

(a) Point out the advantages of vegetative reproduction in plants 

Ans: 1. Vegetative reproduction is a much faster way of reproducing than sexual reproduction, as it does not require the formation of a new organism.

2. It helps to preserve the desired characteristics of a particular plant, as genetic variation is not introduced with vegetative reproduction.

3. It helps plants spread and colonize new areas, as the parent plant can produce multiple offspring simultaneously.

4. It is a good way to produce large numbers of plants quickly, which is beneficial for commercial purposes

 (Any two points) 

(b) Define polyploid breeding

Ans: The number of chromosomal sets in a species can be changed through a process called polyploid plant breeding. The addition of additional sets of chromosomes into a species is a process known as polyploidization that can accomplish this.

Name the chemical used in induced polyploidy. 

Ans: Colchicine

(c) Point out any three advantages of the tissue culture technique

Ans: 1. Rapid Multiplication: Tissue culture is a method for the quick growth of plants and can quickly multiply thousands of plants.

2. Disease-Free Plants: Tissue culture also aids in the production of disease-free, highly pest- and disease-resistant plants.

3. Quality Control: Tissue culture can be used to control plant quality. It assists in preserving the plants’ intended traits.

(d) How is parasitism different from predation? 

Ans: Parasitism is when one organism (the parasite) lives on or in another organism (the host) and benefits from it, while the host is adversely affected. Predation is when one organism (the predator) captures and feeds on another organism (the prey). The predator benefits from eating the prey, while the prey is adversely affected.

(Objective Type Questions) 

3. Choose the correct/most appropriate answer and write in you 

answer-book : 

Question: (i) Define mortality rate. 

Ans: The frequency of deaths in a population is measured by the mortality rate. Typically, it is stated as a ratio (%) of the entire population or as the number of fatalities per 1,000 people annually. Along with other demographic factors, it is also used to calculate the mortality risk for various age groups.

Question: (ii) Translation occurs in: 

(a) Nucleus 

(b) Cytoplasm 

(c) Both (a) and (b). 

(d) None of these 

Answer: (c)

Question: (iii) Define national park. 

Ans: A national park is an area of land protected by the government and managed by either a federal, state or local agency to conserve natural and cultural resources. National parks typically feature scenic landscapes, a variety of wildlife, recreational activities, and educational opportunities.

Question: (iv) The synthesis of organic molecules by green plants represents primary productivity. 

Ans: Primary productivity is the production of organic matter by autotrophs.

Question: Describe the process of double fertilization. What is its significance? (Important)

Ans: Already discussed

Question: What is multiple allelism? Explain with the help of an example. (Important)

Ans: Already discussed

Question: Define genetic code Point out its characteristics. (Important)

Ans: Already discussed

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