Science Chapter 07: Transportation in Animals and Plants

Class 07 Science NCERT

In most animals the blood that circulates in the body distributes food and oxygen to different cells of the body. It also carries waste products from different parts of the body for excretion.

Circulatory system consists of the heart and blood vessels. In humans, blood flows through arteries and veins and the heart acts as a pumping organ.

Blood consists of plasma, RBC, WBC and platelets. Blood is red due to the presence of a red pigment, haemoglobin.

The human heart beats about 70–80 times per minute in an adult person. This is called heart rate.

Arteries carry blood from the heart to all parts of the body. Veins carry blood from all parts of the body back to the heart. Removal of waste products from the body is called excretion.

Excretory system of humans consists of two kidneys, two ureters, a urinary bladder, and urethra. Salts and urea are removed along with water as sweat.

Fish excrete waste substances such as ammonia which directly dissolve in water. Birds, insects and lizard excrete uric acid in semi-solid form. 

Water and mineral nutrients are absorbed by roots from the soil. Nutrients are transported along with water to the entire plant via the vascular tissue called xylem. The vascular tissue for the transport of food to the various parts of the plant is phloem.

A lot of water is lost by plants in the form of vapour through stomata during transpiration. Transpiration generates a force which pulls up water absorbed by the roots from the soil, to reach the stem and leaves.