These DAV Class 7 Science Notes and DAV Class 7 Science Chapter 8 Notes – Transportation in Plants and Animals act as excellent revision resources, particularly in preparation for board exams.
Transportation in Plants and Animals Class 7 DAV Notes
→ Transportation: The movement of substances from one location to another is called transportation.
→ Transportation in Unicellular Organisms: The simple processes; like osmosis; are responsible for transportation of substances in unicellular organisms.
→ Transportation in Complex Organisms: In complex organisms, there is a well developed system for transportation of substances.
→ Transportation in Plants:
→ Transportation of water and minerals:
→ Plants obtain water and minerals from soil.
→ Roots absorb water and minerals through root hairs. A larger number of root hairs increase the area for absorption of water and minerals.
→ The absorbed water and minerals are transported to other plant parts through xylem. Xylem is a network of very fine tubes.
→ Transportation of Food: In plants, food is usually prepared in leaves. From leaves, food is transported to different parts of the plant through phloem. Phloem is also a network of very fine tubes. From storage organs also, food is transported to different plant parts.
→ Transpiration: Loss of water molecules in the form of vapour from plant is called transpiration. Transpiration takes place through minute pores. The pores on leaves are called stomata. The pores on stem are called lenticels. Transpiration plays a major role in transport of water and minerals. Transpiration also plays a major role in photosynthesis.
→ Transportation in Animals:
In higher animals; like human beings; the circulatory system is responsible for transportation of substances. The circulatory system consists of the heart, blood vessels and blood.
→ Heart: The heart is a hollow muscular organ. It lies slightly left from the middle in the chest. The heart pumps blood to different parts of the body. There are four chambers in the heart, viz. right auricle, right ventricle, left auricle and left ventricle. When the heart muscles of a particular chamber contract, it pushes the blood.
→ Flow of Blood through heart:
- Deoxygenated blood from different parts of the body comes to the right auricle.
- From right auricle, the blood is pumped into the right ventricle.
- The right ventricle pumps the blood into lungs. Oxygenation of blood takes place in the lungs.
- From lungs, the oxygenated blood comes into the left auricle.
- From left auricle, the blood is pumped into the left ventricle.
- The left ventricle pumps the blood to different parts of the body.
→ Blood Vessels: Blood vessels make an intricate network of tubes through which the blood flows. Blood vessels are of three types, viz. arteries, veins and capillaries.
→ Arteries: Arteries carry oxygenated blood. Arteries have thick walls, because they have to carry blood under high pressure.
→ Veins: Veins carry deoxygenated blood. Veins have thin walls, because they don’t have to carry blood under high pressure.
→ Capillaries: Capillaries branch out from arteries and meet in veins. Capillaries supply blood to the tissue level and cellular level.
→ Blood: Blood is a fluid which works as carrier for different materials in the body. Blood is composed of blood cells, plasma and platelets.
→ Plasma: The fluid part of the blood is composed of plasma. It is a pale coloured fluid. It makes the largest portion of the blood.
→ Platelets: Platelets play an important role in blood clotting. Blood clotting happens in case of injury and prevents excess loss of blood.
→ Blood Cells: Blood cells are of two main types:
→ Red Blood Cells (RBCs): RBCs contain a red pigment; called haemoglobin. Due to this, the colour of blood is red. Haemoglobin transports oxygen and thus is the main respiratory carrier.
→ White Blood Cells (WBCs): These are of pale colour. WBCs destroy harmful materials, bacteria and dead cells. Thus, they protect us against infections.
- Functions of Blood:
- Blood helps in distribution of digested food to all parts of the body.
- Circulation of blood helps in maintenance of temperature of the body.
- Blood helps in fighting infections.
- Blood transports oxygen from the lungs to different tissues.
- Blood transports carbon dioxide from different tissues to the lungs.
→ Heart Beat and Pulse Rate: A heart beat consists of contraction and relaxation of heart muscles. The contraction of the heart muscles is called systole. The relaxation of the heart muscles is called diastole. The heart’s contraction and relaxation can also be felt as regular pulse or jerks in the main arteries. The pulse rate and the heart rate are same. The heart rate in a normal adult can be from 60 to 80 beats per minute. During vigorous physical activities or at times of excitement, this can go up to 200 beats per minute.
→ Excretion in Animals: The process of removing wastes; produced by living beings; is called excretion. In unicellular organisms, excretion takes place through osmosis. In complex organisms, there is a well developed excretory system for this purpose.
→ Excretory System: The human excretory system is composed of kidneys.
→ Kidneys: A kidney is a bean-shaped organ. Kidney filters waste materials from blood. The waste materials; along with water; form urine. Urine is then transferred through ureters to the urinary bladder. From urinary bladder, urine is expelled from time to time.
Some other organs involved in excretion:
- Digestive System: Undigested food and other waste materials are removed through cloaca.
- Lungs: Carbon dioxide is removed through lungs.
- Skin: Skin produces sweat. Many waste products are eliminated along with sweat.
→ Xylem: Fine capillary tubes in plants which carry water and minerals.
→ Phloem: Fine tubes in plants which carry food.
→ Vascular bundle: The inner part of a plant which is mainly composed of xylem and phloem.
→ Artery: These are thick-walled blood vessels which carry blood from heart to different organs.
→ Veins: These are thin-walled blood vessels which carry blood from different organs to heart.
→ Blood plasma: This is the liquid component of blood.
→ Heart: It is a muscular organ which pumps blood.
→ Systole: Contraction of heart muscles.
→ Diastole: Relaxation of heart muscles.
→ Excretion: The process of removing harmful substances from the body.