ANAND CLASSES study material and notes to enhance your CBSE Class 10 Science Biology preparation with case study-based MCQs on Modes of Nutrition. Understand Autotrophic and Heterotrophic Nutrition with detailed explanations, answers, and examples to excel in your exams.
Case Study 1: Understanding Autotrophic Nutrition
Green plants are capable of synthesizing their own food using simple inorganic substances like carbon dioxide and water in the presence of sunlight. This process is called photosynthesis. The green pigment chlorophyll present in plant cells traps sunlight and facilitates food production. Some bacteria also follow the autotrophic mode of nutrition, although most bacteria are heterotrophic. The organisms that follow autotrophic nutrition are called autotrophs, and they form the base of the food chain by acting as producers.
1. What is the main characteristic of autotrophic nutrition?
a) The organism depends on other organisms for food
b) The organism synthesizes its own food using inorganic substances
c) The organism consumes only dead and decaying matter
d) The organism consumes ready-made organic food
Answer: b) The organism synthesizes its own food using inorganic substances
Explanation: Autotrophic organisms like green plants prepare their own food through photosynthesis using carbon dioxide, water, and sunlight.
2. Which of the following is not an example of an autotroph?
a) Mango tree
b) Cyanobacteria
c) Yeast
d) Algae
Answer: c) Yeast
Explanation: Yeast is a fungus that follows a heterotrophic mode of nutrition, relying on organic matter for survival.
3. Why are autotrophs important in an ecosystem?
a) They consume organic food
b) They produce food for other organisms
c) They depend on other organisms for survival
d) They cannot store energy
Answer: b) They produce food for other organisms
Explanation: Autotrophs (like green plants) form the base of the food chain and supply energy to heterotrophic organisms.
Case Study 2: Heterotrophic Nutrition in Animals and Fungi
Heterotrophic organisms cannot synthesize their own food. They obtain food from autotrophs or other heterotrophs. All animals, fungi, and most bacteria exhibit heterotrophic nutrition. Depending on the source of food, heterotrophic organisms are further classified as herbivores, carnivores, omnivores, saprophytes, and parasites.
4. Which of the following organisms exhibits heterotrophic nutrition?
a) Neem tree
b) Algae
c) Tiger
d) Grass
Answer: c) Tiger
Explanation: A tiger depends on other organisms (prey) for food, making it a heterotroph.
5. Which of these statements about heterotrophic organisms is incorrect?
a) They depend on autotrophs for food
b) They cannot make their own food
c) They produce food through photosynthesis
d) They may consume plants or other animals
Answer: c) They produce food through photosynthesis
Explanation: Heterotrophs cannot produce their own food; they rely on other organisms for nutrition.
6. Fungi obtain nutrients from dead and decaying matter. This mode of nutrition is called:
a) Parasitic
b) Saprophytic
c) Autotrophic
d) Symbiotic
Answer: b) Saprophytic
Explanation: Saprophytes, like fungi, feed on decomposing organic matter to obtain nutrients.
Case Study 3: Interdependence of Autotrophs and Heterotrophs
Autotrophs and heterotrophs are interdependent. Green plants (autotrophs) produce food through photosynthesis, and animals (heterotrophs) consume them for energy. Even carnivores indirectly depend on autotrophs, as they eat herbivores that feed on plants. This energy transfer forms a food chain. The oxygen released by autotrophs is also essential for heterotrophic respiration.
7. Which statement best describes the relationship between autotrophs and heterotrophs?
a) Heterotrophs produce food for autotrophs
b) Autotrophs depend on heterotrophs for energy
c) Heterotrophs depend on autotrophs for food and oxygen
d) There is no relationship between autotrophs and heterotrophs
Answer: c) Heterotrophs depend on autotrophs for food and oxygen
Explanation: Heterotrophs rely on autotrophs for both food (directly or indirectly) and oxygen released during photosynthesis.
8. If all autotrophic organisms disappeared, what would happen to the ecosystem?
a) There would be no effect
b) Heterotrophs would continue to survive
c) Heterotrophs would eventually die due to lack of food
d) New autotrophs would evolve instantly
Answer: c) Heterotrophs would eventually die due to lack of food
Explanation: Without autotrophs, there would be no primary food source, leading to the collapse of food chains and ecosystems.
Case Study 4: Photosynthesis – The Basis of Autotrophic Nutrition
Photosynthesis is the process by which green plants synthesize their own food using sunlight, carbon dioxide, and water. This process takes place in chloroplasts, which contain the green pigment chlorophyll. The reaction produces glucose and oxygen as by-products. The glucose formed is used by the plant for energy, while oxygen is released into the atmosphere. This process is the foundation of life on Earth as it provides food and oxygen for all living organisms.
9. What is the main product of photosynthesis?
a) Oxygen
b) Carbon dioxide
c) Glucose
d) Water
Answer: c) Glucose
Explanation: The primary product of photosynthesis is glucose, which serves as an energy source for the plant. Oxygen is released as a by-product.
10. Which pigment is responsible for capturing sunlight in the process of photosynthesis?
a) Hemoglobin
b) Chlorophyll
c) Melanin
d) Carotene
Answer: b) Chlorophyll
Explanation: Chlorophyll, present in the chloroplasts of green plants, absorbs sunlight and facilitates photosynthesis.
11. Which of the following is not required for photosynthesis?
a) Sunlight
b) Oxygen
c) Water
d) Carbon dioxide
Answer: b) Oxygen
Explanation: Photosynthesis produces oxygen as a by-product but does not require it for the process to occur.
Case Study 5: Types of Heterotrophic Nutrition
Heterotrophic organisms obtain their food from other sources. Based on their feeding habits, they can be classified into different types:
- Holozoic Nutrition: Organisms ingest and digest solid food, e.g., humans, dogs.
- Saprophytic Nutrition: Organisms feed on dead and decaying matter, e.g., fungi, bacteria.
- Parasitic Nutrition: Organisms live on or inside another organism (host) and derive nutrients, e.g., lice, tapeworms.
- Symbiotic Nutrition: Two organisms live together for mutual benefit, e.g., lichens (association of algae and fungi).
12. Which type of heterotrophic nutrition is exhibited by fungi?
a) Holozoic
b) Parasitic
c) Saprophytic
d) Symbiotic
Answer: c) Saprophytic
Explanation: Fungi feed on dead and decaying organic matter, which is known as saprophytic nutrition.
13. Which of the following is an example of a parasitic organism?
a) Mushroom
b) Amoeba
c) Tapeworm
d) Deer
Answer: c) Tapeworm
Explanation: Tapeworms live inside the intestine of animals and absorb nutrients from their host, making them parasites.
14. Which mode of nutrition is observed in humans?
a) Saprophytic
b) Parasitic
c) Holozoic
d) Autotrophic
Answer: c) Holozoic
Explanation: Humans consume solid food, digest it, and absorb nutrients, which is characteristic of holozoic nutrition.
Case Study 6: Importance of Nutrition for Survival
Nutrition is essential for all living organisms as it provides energy for growth, repair, and maintaining bodily functions. Autotrophs like plants produce their own food, while heterotrophs rely on plants and other animals for sustenance. In ecosystems, plants form the primary producers, herbivores act as primary consumers, and carnivores as secondary consumers. Without proper nutrition, life processes cannot be sustained, leading to starvation and eventual death.
15. Why is nutrition important for organisms?
a) To carry out life processes
b) To increase body weight
c) To reduce movement
d) To release carbon dioxide
Answer: a) To carry out life processes
Explanation: Nutrition provides the necessary energy and raw materials for growth, repair, and survival.
16. Which organisms are called primary consumers in a food chain?
a) Herbivores
b) Carnivores
c) Decomposers
d) Autotrophs
Answer: a) Herbivores
Explanation: Herbivores feed directly on plants (autotrophs), making them primary consumers.
17. What would happen if all heterotrophs disappeared from an ecosystem?
a) There would be no effect
b) Plants would grow uncontrollably
c) Nutrient recycling would be disrupted
d) Sunlight would no longer be needed
Answer: c) Nutrient recycling would be disrupted
Explanation: Heterotrophs play a key role in energy transfer and decomposition, which helps maintain ecosystem balance.
Case Study 7: Role of Chlorophyll in Photosynthesis
Green plants use sunlight to prepare their own food through photosynthesis. This process occurs in specialized cell organelles called chloroplasts, which contain the green pigment chlorophyll. Chlorophyll absorbs light energy from the sun, which is then used to convert carbon dioxide and water into glucose and oxygen. The process of photosynthesis is crucial for maintaining the balance of oxygen and carbon dioxide in the atmosphere.
18. What is the role of chlorophyll in photosynthesis?
a) Absorbs water from the soil
b) Converts glucose into oxygen
c) Absorbs light energy from the sun
d) Produces carbon dioxide
Answer: c) Absorbs light energy from the sun
Explanation: Chlorophyll traps sunlight, which is essential for converting carbon dioxide and water into glucose and oxygen.
19. Which of the following is a by-product of photosynthesis?
a) Carbon dioxide
b) Oxygen
c) Nitrogen
d) Sulfur dioxide
Answer: b) Oxygen
Explanation: Photosynthesis produces glucose as food, while oxygen is released as a by-product into the atmosphere.
20. If a plant is kept in complete darkness for a week, what will happen?
a) The plant will continue photosynthesis
b) The plant will produce more chlorophyll
c) The plant will stop making food and eventually die
d) The plant will grow taller than usual
Answer: c) The plant will stop making food and eventually die
Explanation: Without sunlight, the plant cannot perform photosynthesis, leading to starvation and death.
Case Study 8: Different Types of Heterotrophic Nutrition
Heterotrophic organisms do not synthesize their own food; instead, they obtain it from other sources. There are different types of heterotrophic nutrition:
- Holozoic Nutrition: Involves ingestion and digestion of food (e.g., humans, dogs).
- Saprophytic Nutrition: Organisms feed on dead and decaying matter (e.g., fungi, decomposer bacteria).
- Parasitic Nutrition: Parasites derive food from a living host (e.g., lice, tapeworms).
- Symbiotic Nutrition: Two organisms benefit from each other (e.g., lichens – association of algae and fungi).
21. Which of the following organisms follows saprophytic nutrition?
a) Cow
b) Mushroom
c) Amoeba
d) Tiger
Answer: b) Mushroom
Explanation: Mushrooms feed on dead organic matter, making them saprophytes.
22. Which organism shows parasitic nutrition?
a) Deer
b) Tapeworm
c) Grass
d) Mango tree
Answer: b) Tapeworm
Explanation: A tapeworm lives inside the intestine of animals and absorbs nutrients from its host, making it a parasite.
23. Which type of nutrition is exhibited by an amoeba?
a) Holozoic
b) Saprophytic
c) Parasitic
d) Symbiotic
Answer: a) Holozoic
Explanation: Amoeba ingests solid food using pseudopodia and digests it inside food vacuoles, which is a holozoic mode of nutrition.
Case Study 9: Interdependence of Autotrophs and Heterotrophs
Autotrophs and heterotrophs are interdependent in an ecosystem. Autotrophs produce food through photosynthesis, which is then consumed by herbivores. Carnivores depend on herbivores for energy, forming a food chain. Decomposers break down dead organisms, returning nutrients to the soil. Oxygen produced by autotrophs is also essential for respiration in heterotrophs.
24. What is the role of decomposers in an ecosystem?
a) They produce oxygen
b) They decompose dead matter and recycle nutrients
c) They directly consume autotrophs
d) They store energy in food chains
Answer: b) They decompose dead matter and recycle nutrients
Explanation: Decomposers (like fungi and bacteria) break down organic matter and return nutrients to the soil, maintaining ecological balance.
25. Which of the following organisms is an autotroph?
a) Snake
b) Deer
c) Algae
d) Lion
Answer: c) Algae
Explanation: Algae perform photosynthesis and produce their own food, making them autotrophs.
26. What would happen if all autotrophs disappeared from an ecosystem?
a) Heterotrophs would continue to survive
b) Oxygen levels would increase
c) Food chains would collapse
d) New autotrophs would instantly evolve
Answer: c) Food chains would collapse
Explanation: Autotrophs form the base of food chains. Without them, herbivores would die, followed by carnivores, leading to ecosystem collapse.
Case Study 10: Nutrition and Energy Flow in Ecosystems
In an ecosystem, energy flows from producers (plants) to consumers (animals) and finally to decomposers. The energy in an ecosystem is transferred through food chains and food webs. Only 10% of energy is passed from one trophic level to the next, while the rest is lost as heat.
27. Which of the following organisms is a primary consumer?
a) Grass
b) Lion
c) Deer
d) Eagle
Answer: c) Deer
Explanation: Deer eat plants, making them primary consumers in the food chain.
28. What percentage of energy is transferred from one trophic level to the next?
a) 100%
b) 50%
c) 10%
d) 0%
Answer: c) 10%
Explanation: According to the 10% Law of Energy Transfer, only 10% of energy is passed to the next level, while 90% is lost as heat.
29. Which of the following is an example of a food chain?
a) Grass → Deer → Lion
b) Lion → Grass → Deer
c) Deer → Grass → Lion
d) Grass → Lion → Deer
Answer: a) Grass → Deer → Lion
Explanation: In this food chain, grass (autotroph) is eaten by deer (herbivore), which is then consumed by lion (carnivore).
These case study-based MCQs provide a comprehensive understanding of Modes of Nutrition and their role in ecosystems.
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