Test: Nutrition in Plants -1 (UPSC Level) - UPSC MCQ

- Statement 1: Correct. Plants are considered autotrophs because they have the ability to synthesize their own food through the process of photosynthesis, which involves utilizing basic substances like water and carbon dioxide along with sunlight to produce glucose.

- Statement 2: Incorrect. Animals are not autotrophs; they are heterotrophs. Unlike plants, animals cannot produce their own food and must rely on consuming plants or other organisms to obtain their nutrients.

- Statement 3: Correct. The process of nutrition in plants, particularly photosynthesis, involves the use of sunlight, water, carbon dioxide, and minerals to create energy in the form of glucose. This process is vital for the plant's energy requirements and growth.

Thus, the correct answer is Option C: 1 and 3 Only, as statements 1 and 3 are correct, while statement 2 is incorrect.

1. Statement 1: Correct. Cuscuta, also known as Amarbel, is a parasitic plant that lacks chlorophyll, which is why it cannot perform photosynthesis. Instead, it depends on its host plant for nutrients, obtaining them through specialized structures that penetrate the host.

2. Statement 2: Incorrect. Insectivorous plants, such as pitcher plants and Venus flytraps, do not primarily rely on soil for nutrients. They trap and digest insects to compensate for the lack of certain nutrients, particularly nitrogen, that are not sufficiently available in the soil they grow in. Hence, insects are not merely supplementary; they are critical for these plants' nutrient needs.

3. Statement 3: Correct. Saprotrophs, such as fungi, obtain their nutrients by decomposing dead and decaying organic matter. This process is known as saprotrophic nutrition, whereby they release enzymes to break down complex organic substances into simpler compounds, which they then absorb.

Thus, only statements 1 and 3 are correct, making Option C the right answer.

1. Cuscuta - Insectivorous plant: Incorrectly matched. Cuscuta is not an insectivorous plant; it is a parasitic plant. It lacks chlorophyll and derives nutrients from the host plant it attaches to, rather than trapping insects.

2. Pitcher plant - Parasitic plant: Incorrectly matched. The pitcher plant is an insectivorous plant, not a parasitic plant. It captures and digests insects to obtain nutrients that may be lacking in the soil it grows in.

3. Mushroom - Saprotroph: Correctly matched. Mushrooms are saprotrophs. They obtain their nutrients from dead and decaying organic matter through saprotrophic nutrition.

4. Lichen - Symbiotic association: Correctly matched. Lichens are a symbiotic association between fungi and algae. The algae perform photosynthesis and provide food, while the fungi offer protection and help retain moisture.

Thus, only two pairs (Mushroom - Saprotroph and Lichen - Symbiotic association) are correctly matched.

1. Autotrophic Nutrition - Plants creating food using sunlight: Correctly matched. Autotrophic nutrition refers to the process where plants produce their own food using sunlight, water, and carbon dioxide through photosynthesis.

2. Heterotrophic Nutrition - Animals producing their own food: Incorrectly matched. Heterotrophic nutrition involves organisms that cannot produce their own food and depend on other organisms (plants or animals) for nutrition. Animals are generally heterotrophs as they consume food produced by plants or other animals.

3. Photosynthesis - Process of converting carbon dioxide and water into glucose: Correctly matched. Photosynthesis is the process by which plants convert carbon dioxide and water into glucose and oxygen, using sunlight as energy.

4. Mineral Nutrition - Animals obtaining nutrients from soil: Incorrectly matched. Mineral nutrition pertains to plants absorbing minerals from the soil. Animals do not obtain nutrients directly from the soil; instead, they obtain nutrients by consuming plant matter or other animals.

Thus, only pairs 1 and 3 are correctly matched, making the correct answer Option B: Only two pairs.

1. Stomata - Absorb sunlight for photosynthesis: This pair is incorrectly matched. Stomata are pores on the leaf surface that facilitate gas exchange, allowing carbon dioxide to enter and oxygen to exit the leaf. They do not absorb sunlight; their primary role in photosynthesis is related to gas exchange.

2. Chlorophyll - Captures sunlight energy: This pair is correctly matched. Chlorophyll is the green pigment found in the chloroplasts of plant cells. It plays a crucial role in photosynthesis by capturing light energy from the sun, which is then used to convert carbon dioxide and water into glucose and oxygen.

3. Transport vessels - Deliver nutrients and water: This pair is correctly matched. Transport vessels, specifically xylem and phloem, are responsible for the movement of water, minerals, and nutrients throughout the plant. Xylem transports water and dissolved minerals from the roots to the leaves, where photosynthesis takes place.

4. Nucleus - Main site of photosynthesis: This pair is incorrectly matched. The nucleus is the control center of the cell and contains genetic material, but it is not involved in photosynthesis. Photosynthesis occurs in the chloroplasts, which contain chlorophyll.

Thus, only pairs 2 and 3 are correctly matched, making the correct answer "Option B: Only two pairs."

Chlorophyll plays a crucial role in photosynthesis by capturing sunlight energy necessary for synthesizing food from carbon dioxide and water. This process occurs in the chloroplasts of plant cells, where chlorophyll absorbs light energy and converts it into chemical energy, initiating the production of carbohydrates. Without chlorophyll, plants would not be able to carry out photosynthesis effectively, impacting their ability to produce food and oxygen essential for life on Earth.

Statement I is accurate as farmers do indeed spread manure or fertilisers to replenish soil nutrients. Statement II is also correct because plants absorb nutrients from the soil, which can lead to a decline in soil nutrients over time due to this absorption process. Therefore, both statements are true, and Statement II logically explains why farmers need to replenish the soil with manure or fertilisers.

This symbiotic relationship between the two statements highlights the necessity of nutrient management in agricultural practices to ensure the soil remains fertile for crop growth.

Both Statement-I and Statement-II are factually correct. Statement-I highlights the difference in nutritional modes between plants and animals, emphasizing that plants can produce their own food, while animals rely on consuming plants or other animals. Statement-II defines nutrition and explains the terms autotrophic and heterotrophic nutrition, aligning with the context of plant and animal nutrition. Therefore, (a) is the correct option as it accurately reflects the statements and their interrelation.

Statement-I is accurate in describing photosynthesis as the process by which plants produce food, primarily occurring in their leaves. This is a fundamental concept in plant biology. However, Statement-II, comparing living organisms' bodies to how buildings are constructed of bricks, is incorrect. While the analogy aims to simplify the concept of cells being the basic structural unit of living organisms, the comparison to buildings constructed of bricks is not entirely accurate. Cells are the fundamental units of life, but the analogy to bricks in building construction oversimplifies the complexity and functionality of cells within organisms.

Nitrogen plays a crucial role in plant physiology by aiding in the production of proteins and fats. While plants create carbohydrates through photosynthesis using carbon, hydrogen, and oxygen, they require nitrogen to synthesize proteins, which are essential nitrogen-containing compounds. This element is pivotal for plant growth and development, contributing significantly to the formation of vital plant components such as enzymes, chlorophyll, and hormones. Farmers often supplement nitrogen to the soil, either through nitrogen-fixing bacteria or fertilizers, to ensure plants have an adequate supply for synthesizing proteins and other nitrogen-containing compounds essential for their growth and overall health.