NCERT Class 7 Science Chapter 11 - Transportation in Animals and Plants Notes

Chapter 11 - Transportation in Animals and Plants Notes

1. All organisms need food, water and oxygen for survival.

2. In human, circulatory system consists of the heart and blood vessels.

3. Blood is a fluid which transports various essential substances to the body. Blood is the fluid which flows in blood vessels. It transports substances like digested food from the small intestine to the other parts of the body. It carries oxygen from the lungs to the cells of the body. It also transports waste for removal from the body.

4. The fluid part of the blood is called plasma.

5. Blood has three major cells -
• Red Blood Cells (RBC)
• White Blood Cells (WBC)
• Blood platelets

6. Red Blood Cells contain a red pigment called haemoglobin. Haemoglobin binds with oxygen and transports it to all the parts of the body and ultimately to all the cells. It will be difficult to provide oxygen efficiently to all the cells of the body without haemoglobin. The presence of haemoglobin makes blood appear red.

7. White Blood Cells (WBC) fight against germs that may enter our body.

8. Platelets are very small disc-shaped cells present in the blood. They help to clot the blood from a cut or wound.

9. There are 2 types of blood vessels
• Arteries
• Veins

10. Arteries carry oxygen-rich blood from the heart to all parts of the body. Since the blood flow is rapid and at a high pressure, the arteries have thick elastic walls.

11. Pulse is the rate at which the heartbeats and it is due to the blood flowing in the arteries.

12. The number of beats per minute is called the pulse rate. A resting person, usually has a pulse rate between 72 and 80 beats per minute.

13. Veins are the vessels which carry carbon dioxide-rich blood from all parts of the body back to the heart. The veins have thin walls. There are valves present in veins which allow blood to flow only towards the heart.

14. The capillaries join up to form veins which empty into the heart.

15. The heart is located in the chest cavity with its lower tip slightly tilted towards the left. The heart is roughly the size of fist.

16. The heart has four chambers. The two upper chambers are called the atria (singular: atrium) and the two lower chambers are called the ventricles. The partition between the chambers helps to avoid mixing up of blood rich in oxygen with the blood rich in carbon dioxide.

17. The walls of the chambers of the heart are made up of muscles. These muscles contract and relax rhythmically. This rhythmic contraction followed by its relaxation constitute a heartbeat.

18. A doctor uses the stethoscope as a device to amplify the sound of the heart. It consists of a chest piece that carries a sensitive diaphragm, two ear pieces and a tube joining the parts.

19. Animals such as sponges and Hydra do not posses any circulatory system. The water in which they live brings food and oxygen as it enters their bodies. The water carries away waste materials and carbon dioxide as it moves out. Thus, these animals do not need a circulatory fluid like the blood.

20. The process of removal of wastes produced in the cells of the living organisms is called excretion. The parts involved in excretion forms the excretory system.

21. A mechanism to filter the blood is required. This is done by the blood capillaries in the kidneys. When the blood reaches the two kidneys, it contains both useful and harmful substances. The useful substances are absorbed back into the blood. The wastes dissolved in water are removed as urine.

22. From the kidneys, the urine goes into the urinary bladder through tube-like ureters. It is stored in the bladder and is passed out through the urinary opening at the end of a muscular tube called urethra.

23. The kidneys, ureters, bladder and urethra form the excretory system.

24. An adult human being normally passes about 1 - 1.8 L of urine in 24 hours. The urine consists of 95% water, 2.5% urea and 2.5% other waste products.

25. Plants absorb water and minerals by the roots. The roots have root hair. The root hair increase the surface area of the root for the absorption of water and mineral nutrients dissolved in water. The root hair is in contact with the water present between the soil particles.

26. Plants have pipe-like vessels to transport water and nutrients from the soil. The vessels are made of special cells, forming the vascular tissue.

27. A tissue is a group of cells that perform specialised function in an organism.

28. The vascular tissue for the transport of water and nutrients in the plant is called the xylem. The xylem forms a continuous network of channels that connects roots to the leaves through the stem and branches and thus transports water to the entire plant.

29. The food has to be transported to all parts of the plant. This is done by the vascular tissue called the phloem.

30. The English physician, William Harvey discovered the circulation of blood.

31. The way in which waste chemicals are removed from the body of the animal depends on the availability of water. Aquatic animals like fishes, excrete cell waste as ammonia which directly dissolves in water. Some land animals like birds, lizards, snakes excrete a semi-solid, white coloured compound (uric acid). The major excretory product in humans is urea.

32. Sometimes a person’s kidneys may stop working due to infection or injury. As a result of kidney failure, waste products start accumulating in the blood. Such persons cannot survive unless their blood is filtered periodically through an artificial kidney. This process is called dialysis.

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