ANAND CLASSES enhance your CBSE Class 10 Science Biology preparation with Assertion and Reason questions on Modes of Nutrition. Get detailed explanations for better understanding and concept clarity.
Assertion and Reason Questions(Modes of Nutrition) for Class 10 Science Biology
Q1.
Assertion (A): Green plants are autotrophs.
Reason (R): Green plants can synthesize their own food using inorganic materials like carbon dioxide and water in the presence of sunlight.
Answer: (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
Explanation: Green plants have chlorophyll, which helps them trap sunlight energy to perform photosynthesis. This allows them to convert inorganic substances into organic food, making them autotrophs.
Q2.
Assertion (A): All bacteria are autotrophic in nature.
Reason (R): Bacteria contain chlorophyll, which enables them to make their own food through photosynthesis.
Answer: (C) Assertion is false, but Reason is true.
Explanation: While some bacteria (autotrophic bacteria) can make their own food, most bacteria are heterotrophic and depend on other organisms for nutrition. Not all bacteria contain chlorophyll.
Q3.
Assertion (A): Animals depend directly or indirectly on autotrophs for their food.
Reason (R): Animals lack the ability to synthesize their own food from inorganic materials.
Answer: (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
Explanation: Animals are heterotrophs, meaning they cannot produce their own food and must obtain it from plants (autotrophs) or other animals that consume plants.
Q4.
Assertion (A): Non-green plants like yeast are autotrophs.
Reason (R): Non-green plants do not have chlorophyll and cannot synthesize their own food.
Answer: (C) Assertion is false, but Reason is true.
Explanation: Non-green plants like yeast lack chlorophyll and cannot carry out photosynthesis. They rely on external sources for food, making them heterotrophs.
Q5.
Assertion (A): Autotrophs are also known as producers.
Reason (R): Autotrophs synthesize their own food, which forms the base of the food chain.
Answer: (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
Explanation: Since autotrophs make their own food and provide energy to other organisms in an ecosystem, they are called producers. The food they create supports heterotrophic organisms.
Q6.
Assertion (A): Heterotrophs depend on autotrophs for food.
Reason (R): Heterotrophs cannot prepare their own food from inorganic substances.
Answer: (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
Explanation: Heterotrophs, including animals and fungi, rely on other organisms for food because they lack the ability to convert inorganic materials into organic food like autotrophs do.
Q7.
Assertion (A): All green plants are autotrophic.
Reason (R): Green plants contain chlorophyll, which enables them to perform photosynthesis.
Answer: (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
Explanation: Green plants have chlorophyll, which helps them absorb sunlight and convert carbon dioxide and water into food through photosynthesis.
Q8.
Assertion (A): Fungi obtain their nutrition by photosynthesis.
Reason (R): Fungi are heterotrophs that absorb nutrients from dead and decaying organic matter.
Answer: (C) Assertion is false, but Reason is true.
Explanation: Fungi do not perform photosynthesis; instead, they absorb nutrients from decaying matter (saprophytic nutrition).
Q9.
Assertion (A): Autotrophic mode of nutrition is found only in plants.
Reason (R): Only plants have the ability to make their own food using sunlight.
Answer: (D) Both Assertion and Reason are false.
Explanation: While plants are the most common autotrophs, some bacteria (such as autotrophic bacteria) also make their own food. Thus, autotrophy is not exclusive to plants.
Q10.
Assertion (A): All animals are heterotrophs.
Reason (R): Animals cannot synthesize their own food and must obtain it from other organisms.
Answer: (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
Explanation: Animals lack chlorophyll and the ability to carry out photosynthesis, so they rely on plants or other animals for their nutrition.
Q11.
Assertion (A): Non-green plants like Cuscuta (Amarbel) are autotrophs.
Reason (R): Non-green plants can carry out photosynthesis using stored energy.
Answer: (C) Assertion is false, but Reason is true.
Explanation: Non-green plants like Cuscuta lack chlorophyll and cannot perform photosynthesis. They are parasitic heterotrophs that obtain food from a host plant.
Q12.
Assertion (A): Saprotrophic organisms depend on living organisms for food.
Reason (R): Saprotrophic organisms secrete digestive enzymes onto dead and decaying matter to absorb nutrients.
Answer: (C) Assertion is false, but Reason is true.
Explanation: Saprotrophs, like fungi and some bacteria, feed on dead and decaying matter, not living organisms. They decompose organic material externally before absorbing nutrients.
Q13.
Assertion (A): Carnivores are autotrophic organisms.
Reason (R): Carnivores depend on other animals for food.
Answer: (C) Assertion is false, but Reason is true.
Explanation: Carnivores, like lions and tigers, are heterotrophs because they depend on other animals for food. They do not produce their own food like autotrophs.
Q14.
Assertion (A): In a food chain, autotrophs are at the first trophic level.
Reason (R): Autotrophs produce food that is consumed by heterotrophs.
Answer: (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
Explanation: Since autotrophs create their own food and serve as the primary source of energy for all other organisms, they occupy the first trophic level in a food chain.
Q15.
Assertion (A): Autotrophic bacteria can prepare their own food.
Reason (R): All bacteria contain chlorophyll and perform photosynthesis.
Answer: (C) Assertion is true, but Reason is false.
Explanation: Some bacteria, like cyanobacteria, are autotrophic and can make their own food. However, not all bacteria contain chlorophyll or perform photosynthesis. Some autotrophic bacteria use chemosynthesis instead.
Q16.
Assertion (A): Heterotrophic organisms obtain energy directly from the Sun.
Reason (R): Heterotrophs consume food produced by autotrophs or other heterotrophs.
Answer: (C) Assertion is false, but Reason is true.
Explanation: Heterotrophs do not capture sunlight directly; instead, they obtain energy from food made by autotrophs or by consuming other organisms.
Q17.
Assertion (A): Photosynthesis is the only method of autotrophic nutrition.
Reason (R): All autotrophs use sunlight to prepare their food.
Answer: (D) Both Assertion and Reason are false.
Explanation: While photosynthesis is the most common method of autotrophic nutrition, some autotrophs (such as chemosynthetic bacteria) use chemical energy instead of sunlight to prepare their food.
Q18.
Assertion (A): Non-green plants are heterotrophic.
Reason (R): Non-green plants lack chlorophyll and cannot synthesize their own food.
Answer: (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
Explanation: Since non-green plants do not have chlorophyll, they cannot perform photosynthesis and must rely on other organisms for food. Examples include Cuscuta (a parasitic plant) and fungi like yeast.
Q19.
Assertion (A): Chlorophyll is necessary for autotrophic nutrition.
Reason (R): Photosynthesis requires chlorophyll to trap sunlight energy.
Answer: (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
Explanation: Chlorophyll helps autotrophic organisms absorb sunlight, which is essential for photosynthesis. Without chlorophyll, plants cannot produce their own food.
Q20.
Assertion (A): Insectivorous plants are completely autotrophic.
Reason (R): Insectivorous plants perform photosynthesis and trap insects for additional nutrients.
Answer: (C) Assertion is false, but Reason is true.
Explanation: Insectivorous plants like the Venus flytrap and pitcher plant can photosynthesize, but they also obtain additional nutrients, like nitrogen, by digesting insects. This makes them partially heterotrophic.
Q21.
Assertion (A): Animals depend only on autotrophs for food.
Reason (R): All heterotrophs obtain food from green plants directly.
Answer: (D) Both Assertion and Reason are false.
Explanation: Some heterotrophs, like carnivores, obtain food from other heterotrophs instead of directly from autotrophs. For example, a tiger eats deer, which is a herbivore (primary consumer).
Q22.
Assertion (A): Heterotrophic organisms break down complex organic food materials into simpler forms before absorption.
Reason (R): Digestion helps in breaking down food into simpler molecules that can be absorbed by the body.
Answer: (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
Explanation: Heterotrophs cannot directly absorb complex food molecules. They use digestion to break down food into simpler forms before absorption.
Q23.
Assertion (A): Herbivores are primary consumers in the food chain.
Reason (R): Herbivores directly depend on autotrophs for food.
Answer: (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
Explanation: Herbivores (like cows and deer) eat plants (autotrophs) and serve as the first consumers in the food chain.
Q24.
Assertion (A): Saprophytic organisms feed on living organisms.
Reason (R): Saprophytes obtain nutrients from dead and decaying matter.
Answer: (C) Assertion is false, but Reason is true.
Explanation: Saprophytes, such as fungi and some bacteria, feed on dead and decaying organic matter, not living organisms.
Q25.
Assertion (A): Autotrophic nutrition is more energy-efficient than heterotrophic nutrition.
Reason (R): Autotrophs convert solar energy directly into food, while heterotrophs obtain energy indirectly.
Answer: (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
Explanation: Autotrophs convert sunlight directly into chemical energy, while heterotrophs must consume other organisms, losing some energy at each trophic level.
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