Class 7 Science Chapter 1 MCQ

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.

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.

Generally, leaves are the food factories of plants. The synthesis of food in plants occurs in leaves. Carbon dioxide from air is taken in through the tiny pores present on the surface of the leaves. These pores are surrounded by ‘guard cells’. Such pores are called “stomata”.

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.

The leaves have a green pigment called chlorophyll. It helps leaves to capture the energy of the sunlight. This energy is used to synthesise (prepare) food where solar energy is converted into chemical energy.

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

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.

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.

These organisms (yeast, mushrooms and bread-mould) are called “fungi”. They have a different mode of nutrition. They secrete digestive juices on the dead and decaying matter and convert it into a solution. Then they absorb the nutrients from it. This mode of nutrition in which organisms take in nutrients in solution form from dead and decaying matter is called “saprotrophic nutrition”. Plants which use saprotrophic mode of nutrition are called “saprotrophs”.

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).

Mushroom is an example of saprophytes. Mushroom is a fungus which grows under the warm condition on dead parts of plant (e.g. rotting wood of a dead tree) and animals. They obtain nutrition from decaying organic matter. So, they are saprophytes.

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.

Phloem is the tissue in plants that transport food to the parts of the plant where it needs to go. Phloem is composed of various specialized cells called sieve tubes, companion cells, phloem fibres, and phloem parenchyma cells.

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.

Photosynthesis is a process by which green plants make their own food from CO2 and H2O by using solar energy in the presence of chlorophyll. During the process oxygen is released.

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.

Autotrophs are organisms that make food themselves from simple substances like water, CO2 in the presence of sunlight and chlorophyll, e.g. Green plants. Heterotrophs are organisms, which cannot make their own food and take in food prepared by the plants, e.g. Animals and humans Parasites are organisms, which live and derive nutrition from another organisms, called host, e.g. Cuscuta plant. Saprophytes are organism, which obtain nutrition from dead and decaying organic matter, e.g. Fungi, bacteria etc.