Test: Nutrition in Plants- 1 - UPSC 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 green pigment in the leaves responsible for capturing sunlight, which is crucial for photosynthesis. Chlorophyll absorbs light most efficiently in the blue and red wavelengths, while reflecting green light, which is why plants appear green. An additional interesting fact is that chlorophyll is structurally similar to hemoglobin in blood, but instead of iron, it has magnesium at its core.

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.

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.

• 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.

Iodine solution is used to test for the presence of starch. When applied to a leaf, it turns blue-black if starch is present, indicating that photosynthesis has occurred.