Class 7 Science Chapter 1 MCQ

Photosynthesis also takes place in other green parts of the plant — in green stems and green branches. The desert plants have scale- or spine-like leaves to reduce loss of water by transpiration. These plants have green stems which carry out photosynthesis.

A greenhouse is built of any material through which light can pass, such as glass or plastic. Farmers get many advantages like the crops grow well.

Symbiosis is an association between two different organisms that live together and help each other to survive, e.g. lichen (association between an alga and fungus).

Pitcher plant derives nutrition just the way any other plant does. It takes water and minerals from the soil and food by photosynthesis. But the soil in which it grows doesn’t has nitrogen so it uses the pitcher for killing small insects and then digesting them to derive nitrogen from the animal.

All mosquitoes breed in water. A mosquito during its life cycle passes through different modes of nutrition. The larva feeds on microorganisms. The Adult female feeds on blood to supply proteins for eggs and adults of both sucks feed on plant nectar. So, it is most appropriate to considered them as an omnivore.

Pitcher plant has modified leaves that help to trap insect to obtain nitrogen compounds. Thus, it is an insectivorous plant.

The process by which living organisms obtain their food is called “mode of nutrition”. In non-green plants and animals, their mode of nutrition is “heterotrophic”, as they obtain food from plants or other animals.

Saprophytic nutrition is scene in yeast, mushroom and bread mould. In this mode of nutrition, organisms obtain their food from dead and decaying organic matter. Such organisms are known as saprophytes.

Every plant gets their nutrients from soil. A pitcher plant smells good to trap insects when it lacks some nutrients which it fulfills by eating insects. Therefore, insects help in the enrichment of insectivorous plants like Pitcher Plant and Venus Flytrap. A pitcher plant feeds on insects to obtain essential nitrogen and amino acids.

The mode of nutrition is which organisms depend on other for their food is called heterotrophic nutrition. An organism that takes their food or nutrient from others, without giving anything in return, called “parasitic nutrition”. And the body in which he lives is called a “host” and they take nutrients from the body of host and gradually parasite harms them and possible causing death.

Pitcher plant is an insectivorous plant that grow only in soils which do not contain sufficient nitrogen. These plants trap insects by various methods, kill them and digest then to obtain nitrogen compounds for their growth.

Chlorophyll, sunlight, carbon dioxide and water are necessary to carry out the process of photosynthesis. During the process oxygen is released. The carbohydrates ultimately get converted into starch. The presence of starch in leaves indicates the occurrence of photosynthesis. The starch is also a carbohydrate.

Carbon dioxide is the raw material of photosynthesis that is available in air. It is taken by the plant through the tiny pores, called stomata, present on the surface of leaves. The Other necessary conditions are the presence of water, chlorophyll and sunlight. (Oxygen is released during the process, hydrogen comes from water and nitrogen has no role in photosynthesis).

Statement [A] is correct. All green plants are autotrophs. They can make their own food from simple substances like CO2 and H2O by the process of photosynthesis. Oxygen gas produced during this process is liberated into the air. The other statements in correct form are: Most animals are heterotrophs and CO2 is essential for photosynthesis.

In organisms called lichens, a chlorophyll-containing partner, which is an alga, and a fungus live together. The fungus provides shelter, water and minerals to the alga and, in return, the alga provides food which it prepares by photosynthesis. Heterotrophs are dependable organisms while saprotrophs are not. Thus, an autotroph and a heterotroph make a perfect match for each other.

Stomata are the numerous small openings observed on the lower surface of a leaf. Each of these pores is surrounded by a pair of guard cells. The stomata help in the exchange of gases (CO2 goes in and O2 is released out).

Generally, leaves have a green pigment called chlorophyll which absorb the sunlight and makes food for the plant by the process of photosynthesis.

Chlorophyll is the green pigment present in leaves of plants that absorbs sunlight energy, to carry out photosynthesis. In the absence of chlorophyll, the leaves would not be able to capture sunlight energy. Therefore, no photosynthesis can occur.

Plants synthesise their food with the help of chlorophyll. It helps to capture the energy of Sunlight. Plants get raw materials form surroundings. So, we find that sunlight, chlorophyll, carbon dioxide and water are necessary components to carry out the process of photosynthesis. And carbohydrates produced and ultimately converted into starch. During this process oxygen is released which is very essential for the survival all living organisms.

A yellow tubular structures twining around the stem and branches of a tree. This is a plant called “Cuscuta” (Amarbel). It does not have chlorophyll. It takes readymade food from the plant on which it is climbing. As it deprives valuable nutrients, from the body of host. Hence, it is called a parasite.

When a goat eats all the leaves of a small plant. Still new leaves could be seen sprouting in the plant again. This is just because the small plant survived on the food stored in the stem and roots. It might have undergone gaseous exchange through lenticels on stem.

We see slimy, green patches in ponds or in other stagnant water bodies. These are generally formed by the growth of organisms called “algae”. They contain chlorophyll. Algae can also prepare their own food by photosynthesis, so they are known as “Autotrophs”. We have also seen fluffy patches of white, green, brown color growing on rotting wood during the rainy season. These organisms are called “fungi”. They take in nutrients in solution form from dead and decaying matter, called “Saprotrophs”.

Insectivorous plant are green and can-do photosynthesis. So, they are called autotrophs. But they can’t get sufficient nutrients from soil so, they trap insects and digest them. Due to this, they are called “partial heterotrophs”.

A greenhouse is built of any material through which light can pass, such as glass or plastic. Farmers get many advantages like the crops grow well.

Carbohydrate in wheat to encourage the growth of yeast and other saprophytic fungi. They breakdown carbohydrates into simpler compounds like carbon dioxide and alcohol that leads to a foul smell.