Ans) The process of taking in food and utilising it is called nutrition.

Ans) The mode of nutrition in which an organism makes its own food from simpler inorganic substances like CO, and water with the help of sunlight is called autotrophic nutrition.

Ans) The saliva moistens the food for easy swallowing. It contains a digestive enzyme called salivary amylase, which breaks down starch into sugar.

Ans) Autotrophic nutrition takes place through the process of photosynthesis. Presence of carbon dioxide, water, chlorophyll and sunlight are the necessary conditions for autotrophic nutrition. Carbohydrates (food) and oxygen are the by-products of photosynthesis.

Ans) During a single cycle, blood goes twice in the heart which is known as double (NCERT) circulation. It is necessary in human beings to separate oxygenated and deoxygenated blood because this makes their circulatory system more efficient and helps in maintaining constant body temperature.

Ans) Fats are present in the form of large globules in the small intestine. The bile salts from liver break the large fat globules into smaller globules so that the pancreatic enzyme lipase can easily act on them. This is called emulsification of fats. The walls of the small intestine contain glands which secrete intestinal juice. The enzymes present in it finally convert the fats into fatty acids and glycerol. The process of digestion of fats takes place in small intestine.

Ans) Plants can get rid of excess of water by transpiration. Many plant waste products are stored in cellular vacuoles. Waste products are also stored in leaves that fall off. Other waste products are stored as resins and gums, especially in old xylem. Plants also excrete some waste substances into the soil around them. Oxygen released during photosynthesis is also a waste product for plants.

Ans) In highly organised plants, there are two types of conducting tissues-xylem and phloem. Xylem conducts water and minerals obtained from the soil (via roots) to the rest of the plant. Phloem transports food materials from leaves to different parts of the plant body.

Ans) It is necessary to separate deoxygenated and oxygenated blood to maintain efficient (NCERT) supply of oxygen into the body. This system is essential in animals that have high energy need. For example, mammals and birds constantly use this energy to maintain their body temperature.

Ans) The inner lining of small intestine has numerous tiny finger-like projections called villi. These villi increase the surface area for more efficient food absorption. Within these villi, many blood vessels are present that absorb the digested food and carry it to the blood stream. From the blood stream, the absorbed food is delivered to each and every cell of the body.

Ans) The gastric glands in the wall of the stomach release hydrochloric acid, a protein digesting enzyme called pepsin and mucus. The hydrochloric acid creates an acidic medium which facilitates the action of the enzyme pepsin. The hydrochloric acid also kills many bacteria and other micro-organisms that enter along with the food.

Ans) For photosynthesis, plants get carbon dioxide (CO2) gas from atmosphere through stomata, water absorbed from soil and solar energy from sun.

Ans) Chemical equation of photosynthesis-

Ans) Heterotrophic Nutrition – “The organism which do not prepare their own food but depends upon plants and animals for their food. The nutrition of such an organism is called heterotrophic nutrition. Example All animals.

Ans) To maintain life, organism have to perform certain function like nutrition, respiration, reproduction and excretion etc, these basic essential procedures performed by an organism are called life processes.