Test: Nutrition in Plants- 1 - Class 7 MCQ

Autotrophic nutrition is the process by which organisms, such as plants, algae, and some bacteria, synthesize their own food from simple inorganic substances like carbon dioxide and water, typically using sunlight through photosynthesis.

Chlorophyll is the pigment in leaves responsible for capturing sunlight. Here’s why:

• Role in Photosynthesis: Chlorophyll absorbs sunlight, which is essential for photosynthesis, converting light energy into chemical energy.

Organisms that derive nutrients from dead and decaying matter are called saprotrophs. They secrete digestive enzymes onto the decaying material to break it down and absorb the nutrients. Fungi, such as mushrooms and molds, and certain bacteria are common examples of saprotrophs. An interesting fact is that saprotrophs play a crucial role in ecosystems by recycling nutrients back into the soil, supporting plant growth.

Stomata are tiny pores located on the surface of leaves that allow the exchange of gases, including the intake of carbon dioxide and release of oxygen during photosynthesis. Each stoma is surrounded by guard cells that regulate its opening and closing. An interesting fact is that the number of stomata can vary greatly between different plant species and environmental conditions, helping plants adapt to their surroundings.

In lichens, fungi and algae live in a symbiotic relationship where the fungi provide shelter and minerals, while the algae perform photosynthesis and provide food.

Saprotrophs are organisms that obtain their nutrients from dead and decaying matter. The primary example of saprotrophs is fungi. Here are some key points about them:

• Fungi absorb nutrients from their surroundings, such as rotting wood or spoiled food.
• They play a crucial role in the ecosystem by breaking down organic material, which helps recycle nutrients.
• Fungi can grow on various surfaces, including bread, pickles, and leather, especially in warm and humid conditions.
• They reproduce through spores, which are often found in the air and can lead to rapid growth when they land on suitable surfaces.

Understanding saprotrophs is essential as they contribute significantly to nutrient cycling in the environment.

A parasite is an organism that lives on or inside another organism (called the host) and gets its nutrients from the host, often harming it in the process.

• Algae are simple, plant-like organisms that can make their own food using sunlight (photosynthesis).
• Cuscuta is a type of plant that cannot make its own food. Instead, it wraps around other plants and takes nutrients from them. This makes Cuscuta a parasite.
• Mushrooms are fungi that get their nutrients from decaying organic matter. They are not considered parasites because they do not take nutrients from a living host.
• Yeast is also a type of fungus that typically gets its nutrients from sugar. It is not a parasite because it doesn't harm a host organism.

Therefore, the correct answer is B) Cuscuta because it relies on other plants for its nutrients, making it a parasite.

Photosynthesis requires carbon dioxide, water, and sunlight to produce carbohydrates and oxygen. Thus they are raw materials for photosynthesis. Oxygen is a byproduct of photosynthesis, not a raw material required for the process. The process consumes carbon dioxide and water in the presence of sunlight, releasing oxygen as a byproduct

The correct answer is: d) Parasites

Explanation:

Plants that obtain their food from other living plants are called parasites. They attach themselves to the host plant and draw nutrients from it.

Other options:

• a) Autotrophs – These make their own food through photosynthesis (like most green plants).

• b) Omnivores – Animals that eat both plants and animals; not related to plants.

• c) Saprotrophs – Organisms that get food from dead and decaying matter, not from living plants.

So, the correct and most suitable answer is Parasites.

 The correct answer is B: Iodine Test.

•  The iodine test is a simple and widely used method to detect the presence of starch in leaves.
•  To perform this test, a leaf is submerged in boiling water to soften it, then placed in alcohol to remove chlorophyll, making it easier to see the color change.
•  The leaf is then treated with iodine solution.
•  If starch is present, the iodine will cause the leaf to turn a blue-black color, indicating a positive result.