Science 2 Marks Questions

All living organisms require food to survive. It gives them energy to perform various activities. All activities such as playing, running, walking, studying, etc. require energy. The various components present in our food such as carbohydrates, proteins, fats, vitamins, and minerals provide energy to our body. These are also important for growth and development of the body.

Soil has certain bacteria that convert gaseous nitrogen into a usable form and release it into the soil. These soluble forms are absorbed by the plants along with water. By adding fertilizers rich in nitrogen to the soil farmers also made nitrogen available for plants.

Water and minerals are transported to the leaves by the vessels which run like pipes throughout the root, stem, branches and the leaves. These vessels are xylem and phloem, forming a continuous path or passage for the nutrients to make them reach the leaf.

Rhizobium is a type of bacteria that cannot make its own food and lives in the roots of gram, peas, moong beans and other legumes, it converts atmospheric nitrogen into useable form which increases the fertility of soil, and legumes provide food and shelter to the bacteria.

All living organisms require food. Plants can make their food themselves by organic substances but animals including humans cannot make their food themselves. They get it from plants or animals that eat plants. Thus, humans and animals are directly or indirectly dependent on plants.

There are few plants which can trap insects and digest them. Such plants may be green or of some other colour. Such insect-eating plants are called insectivorous plants.
Example: Venus Flytrap and Pitcher plant.

I am white and soft. I grow well in the rainy season. Children pluck me from the ground and admire me. I absorb nutrients from decomposed dead parts of plants and animals in the soil. Mushroom, saprophyte. Explanation: Fungi such as mushroom under warm conditions grow on dead parts of plants (e.g. rotting wood of a dead tree) and animals. They obtain nutrition from decaying organic matter. So, they are saprophytes.

Plants cannot take nitrogen in free state present in the atmosphere. They absorb the nitrogen fixed in the soil by roots, or by symbiotic relationship that are capable of nitrogen fixation from the air with microorganisms.

Some organisms live together and share shelter and nutrients. This is called symbiotic relationship. E.g. an alga, and a fungus live together fungus provides shelter, water and minerals to the alga and, in return, the alga provides food which it prepares by photosynthesis. In this kind of association both partners are benefited.

Organism needs food to:

• Get energy to do work.
• Build body.
• Repair damage in the body.
• Maintain the functions of the body.

Nutrients are chemical substances present in our food that provide energy and other materials required by the body to live and grow.Examples of nutrients are:

1. Carbohydrates.
2. Proteins.
3. Fats.
4. Minerals.
5. Vitamins.

It is true that these animals do not eat plants. They hunt and eat herbivorous animals like deer, gaur, bison, zebra, giraffe, etc. which are dependent on plants for food. If there are no plants, herbivorous animals will not survive and in that case animals like tiger, wolf, lion and leopard will have nothing to eat.

In both the plants, shoot system and leaves are above ground. They prepare food through photosynthesis and transport it to the underground parts for storage.

1. Herbivores: Plant eaters e.g. cow, buffalo, goat etc.
2. Carnivores: Meat eaters e.g. lion, tiger etc.
3. Omnivores: eat both plants and animals e.g. human, bear etc.

Yes, plants having deep red, violet or brown coloured leaves can also carry out photosynthesis because they contain chlorophyll. But their green colour of chlorophyll is masked by the large amount of all other coloured pigments.

Labelled figure is given below: Note: stomata are the tiny pores for gaseous exchange present on leaf surface. Their opening and closing is controled by guard cells.

Yes, the fungi reproduces by spores which are generally present in the air and grow on any article that are left in hot and humid weather for a long time. During rainy season they land on wet and warm things and begin to germinate and grow.

Plants cannot absorb nitrogen in gas form, they need it in soluble form. Therefore, they use the nitrogen present in soil to prepare proteins.
Atmospheric nitrogen is fixed in soil by nitrogen-fixing bacteria such as Rhizobium, which live in the root nodules of leguminous plants such as gram, peas, beans, etc. In return, the plants provide food and shelter to the bacteria.

	Parasite		Saprotroph
i.	Parasite derives nutrients form the living organism.	i.	They derive nutrients from dead and decaying organism.
ii.	Parasites mostly live on or in the host.	ii.	They live on dead and decaying stuff.

The mode of by which parasitic organism get and synthesize their food is called parasitic nutrition. Example Cucuta. It does not have chlorophyll; it takes readymade food from the plant on which it is climbing. The plant on which it climbs is called a host. In a parasitic nutrition only one of the partners is benefited and other is not.

There are vessels inside a plant which run like pipes throughout the root, stem branches and leaves, by going through these vessels water and minerals are transported to leaves from roots.

I am tall but I cannot move. I am green and can prepare my own food. tree, autotroph.

Nutrients are replenished in soil by following ways:By spreading manure or fertilizers that contain nutrients such as nitrogen in the fields.
By the bacterium Rhizobium that is commonly present in rot nodules of leguminous plant that can take atmospheric nitrogen and convert it into a soluble form like nitrates.

Leaves are called food factory of plants, as the synthesis of food takes place in leaves of plants. Water and minerals present in soil are absorbed by roots and transported to leaves via stem. Carbon dioxide from air is taken in through tiny pores on surface of leaves called stomata.

• Organisms derive nutrition from the body of other living organisms (host) are parasites. e.g. Cuscata (amarbel).
• Organisms which organisms derive nutrition from dead and decaying organisms are called saprotrophs. e.g. Mushrooms.

Plants store the food that they produced by photosynthesis in the stem and roots. So, when goat ate away all the leaves of the plant, the plant fulfilled its requirement by the food stored in stem and roots.

Food is the basic need of all living organisms and plants are the basic source of food for all the organisms, and prepare food by the process of photosynthesis. So, if there is no photosynthesis, life would be impossible.

Symbiosis is the type of nutrition in which two different kinds of organisms depend on each other for their nutrition. In this both the organisms are benefitted by each other e.g., lichen is a symbiotic association between algae and fungi. In this one alga and one fungus live together and remain in symbiotic relationship.

Chlorophyll is the green colour pigment which helps leaves to capture energy from sunlight to carry out the food making process of plants by the leaves. It is the green photosynthesis pigment which provides energy necessary for photosynthesis.

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. Example Fungi that secrete digestive juices on the dead and decaying matter and convert it into a solution. Then they absorb the nutrients from it.

Photosynthesis is the food manufacturing process of green plants containing chlorophyll, in presence of sunlight, with the help of carbon dioxide and water to synthesise carbohydrates.
The equation for the process is as follow:
Carbon dioxide + water → carbohydrate + Oxygen

Green plants are called autotrophs as they prepare their own food from simple substances, but animals and most other organisms are called heterotrophs as they take in ready-made food prepared by the plants.

Carbohydrates, proteins, fats, vitamins and minerals are essential components of food, these components are called nutrients, but Nutrition is the mode of taking food by an organism and its utilisation by the body.

When an insect lands in the pitcher, the lid closes and the trapped insect gets entangled into the hair. The insect is digested by the digestive juices secreted in the pitcher.

The cell is enclosed by a thin outer boundary, called the cell membrane Many cells have a distinct, centrally located spherical structure called the nucleus. The nucleus is surrounded by a jelly-like substance called cytoplasm.

Presence of starch in leaves can be tested by iodine test. Iodine turns starch solution into blue-black colour. Pour few drops of dilute iodine solution on the boiled leaf. The leaf becomes blue-black which proves the presence of starch in it. The starch is a carbohydrate.

I live in water; people keep me in an aquarium and feed me. Fish, heterotroph. Explanation: Fish is an aquatic animal. It is kept in aquarium by people. It cannot make its own food. So, its heterotroph.

1. Parasitic plants.
2. Saprophytic plants.
3. Insectivorous (Carnivorous) plants.
4. Symbiotic plants.

1. Sunlight.
2. Carbon dioxide.

Labelled figure is given below:

I am small and I can fly. I disturb your sleep, bite you and suck your blood which is my food. Mosquito, omnivore.
A mosquito during its life cycle passes through different modes of nutrition. The larvae feeds on microorganisms, the adult female feeds on blood to supply proteins for eggs and adults of both sexes feed on plant nectar. So it is most appropriate to consider them as an omnivore.

Animals like tiger, wolf, lion and leopard are carnivores and do not eat plants. They hunt and eat herbivorous animals like deer, gaur, bison, zebra, giraffe, etc., which are dependent on plants for food. If there are no plants, herbivorous animals will not survive and ultimately animals like tiger, wolf, lion and leopard will have nothing to eat.