Botany: Solved Previous Year’s Question Paper for NCERT/CBSE Class 12th Botany Paper Code (HSEIIRKON17—–15320-A)
(Long Answer Type Questions)
Question: With the help of a flow diagram explain the flow of energy in an Ecosystem.
Ans: → Solar Energy from Sun → Plants (Photosynthesis) → Consumers (Herbivores) → Consumers (Carnivores) → Decomposers (Bacteria and Fungi) → Nutrients (Carbon Dioxide, Nitrogen, etc.) → Plants (Respiration) → Consumers (Herbivores) → Consumers (Carnivores) → Decomposers (Bacteria and Fungi) → Nutrients (Carbon Dioxide, Nitrogen, etc.) → Solar Energy from Sun
(Short Answer Type Questions)
Question: What do you understand by a Test Cross? What is its importance?
Ans: A test cross is a breeding experiment used to determine the genotype of an organism. It is used to determine whether the organism is homozygous or heterozygous for a certain trait.
A test cross is important because it can help scientists to understand the genetic makeup of an organism and help them to develop new breeding strategies.
It is also an important tool for understanding inheritance patterns in organisms.
Question: What are the possible benefits and hazards of GM crops?
Ans: Benefits: 1. GM crops are designed to be more resistant to pests and diseases, reducing the need for pesticide use.
2. They can be modified to be more nutritious, increasing the number of vitamins and minerals available to those who consume them.
3. GM crops require less water and fertilizer than traditional crops, making them more sustainable and reducing environmental damage caused by agricultural practices.
4. GM crops can be modified to grow in adverse conditions, such as drought or cold temperatures, increasing crop yields in areas that traditionally had limited crop options.
Hazards: 1. There is a risk of GM crops transferring their modified genes to traditional crops, potentially leading to unexpected environmental consequences.
2. There is a risk of GM crops becoming invasive, outcompeting native species and disrupting the natural balance of local ecosystems.
3. There is a risk that GM crops could have an unknown effect on human health due to the lack of long-term studies on the safety of consuming them.
4. There is a risk that GM crops could lead to an increased reliance on single varieties, reducing crop diversity and leaving farmers vulnerable to disease or environmental changes.
Question: Name various Ozone depleting substances. What is the effect of Ozone layer depletion on living objects?
Ans: Ozone-depleting substances include chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), halons, carbon tetrachloride, methyl bromide, and methyl chloroform. The depletion of the ozone layer has serious implications for living organisms. It increases the amount of ultraviolet radiation (UV-B) reaching the Earth’s surface, which can lead to skin cancer, cataracts, immune system suppression, and damage to plants and animals. It can also disrupt food production and the global climate system.
(Very Short Answer Type Questions)
Question: Differentiate between Anemophilous and Entomophilous flowers.
Ans: Anemophilous flowers are wind-pollinated flowers. They are typically small, inconspicuous, and lack a scent or nectar. Examples of anemophilous flowers include grasses, trees, and other plants.
Entomophilous flowers are insect-pollinated flowers. They are typically brightly coloured and have a sweet scent and/or nectar to attract insects. Examples of entomophilous flowers include daisies, roses, and other flowering plants.
Question: Write a short note on Polyembryony
Ans: Polyembryony is a phenomenon in which multiple embryos develop from a single egg. This process is seen in invertebrates, such as hymenoptera and some lizards, as well as in some plants. In animals, the embryos can be identical or of different sexes, depending on the species. In plants, embryos can be of the same or different varieties. Polyembryony is believed to be a form of asexual reproduction and can occur naturally or can be induced by environmental factors or artificial methods.
Question: What do you understand by Single cell protein SCP? Give two examples of SCPs.
Ans: Single-cell protein (SCP) is a type of food made from live microbial cells. It is made from bacteria, fungi, and algae either grown in a lab or harvested from natural sources. SCP is considered a sustainable food source, as it requires fewer resources to produce than traditional animal proteins. Two examples of SCPs are Spirulina and Chlorella, which are both types of algae.
Question: What does the Ex Situ conservation of biodiversity mean? Give two examples of Ex Situ conservation strategy.
Ans: Ex Situ conservation of biodiversity is a method of conservation in which living organisms are taken out of their natural habitats and placed into a controlled environment. This strategy is used to protect species from the threats of climate change, habitat destruction, and other human activities. Examples of Ex Situ conservation strategies include:
1. Captive breeding:
2. Seed banks:
(Objective Type Questions)
Question: Write the correct/most appropriate answer in your answer
(i) Which of the following is a Mendelian Principle
(a)Co-dominance
(c) Segregation
(b) Multiple alleles
(d) Linkage
Answer: (c) Segregation
(ii)Azadirachtin is a biofertilizer (True/False)
Ans: True
(iii) Which one of the following is green manure/biofertilizer?
(a) Sesbania
(c) Oat
(b) Rice
(d) Maize
Answer: (a) Sesbania
(iv) Animals that can tolerate a narrow range of salinity are called……
Answer: Halophiles
(v) Tip of an ecological pyramid is occupied by:
(a) Producers
(b) Herbivores
(c) Carnivores
(d) None of these
Answer: (a) Producers
(Long Answer Type Questions)
Question: State and explain Mendel’s Law of Segregation. Give reasons for its universal acceptance.
Ans: Already discussed
Question: Explain the mechanism of gene regulation in prokaryotes with the help of lac-operon.
Ans: Already discussed
Question: With the help of one example in each explain briefly the following terms:
(a) Predation
(b) Parasitism
(c) Commensalism
(d) Mutualism
Also, categorize them as positive and negative interactions.
Ans: Already discussed
Question: Define double fertilizations found in angiosperms. Point out its significance.
Ans: Already discussed