Test: Nutrition in Plants- 1 - Class 7 MCQ

The primary mode of nutrition for plants is autotrophic nutrition, where they synthesize their own food using sunlight, carbon dioxide, and water. This process, known as photosynthesis, occurs mainly in the leaves of plants due to the presence of chlorophyll. An interesting fact is that photosynthesis not only produces food but also releases oxygen, which is essential for the survival of most living organisms on Earth.

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.

Plants 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, 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.

Fungi are saprotrophs, meaning they obtain nutrients by decomposing dead and decaying organic matter, playing a crucial role in nutrient cycling.

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. Oxygen is a byproduct, not a raw material.

• Some plants lack chlorophyll and rely on other plants for nourishment using a method called heterotrophic nutrition.
• This type of plant nutrition is known as Heterotrophic nutrition, making these plants 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.