Ch7 - Science PDF

# Long Answers 1. List various functions of blood. * The functions of blood are: * Blood transport **nutrients** to various parts of the body. * It transports **O₂** from the lungs of the tissues and **CO₂** from the tissues to the lungs. * It transports waste pro...

# Long Answers 1. List various functions of blood. * The functions of blood are: * Blood transport **nutrients** to various parts of the body. * It transports **O₂** from the lungs of the tissues and **CO₂** from the tissues to the lungs. * It transports waste product from tissues to the kidneys. * Blood transports **hormones, minerals, vitamin, and water** from one part to another. * Blood regulates body temperature by uniform distribution of heat to all the body parts. * White blood cells protect the body against the diseases. 2. Give a schematic flow of blood from the **heart** to the body and back to the **heart**. * The diagram shows the **heart**, which is the centre of the circulatory system, and the blood flow through veins and arteries. * The blood flow starts from the **vena cava**, which is the main vein that carries deoxygenated blood from the body to the **right atrium**. * From the **right atrium**, the blood goes to the **right ventricle**, which pumps it through the **pulmonary artery** to the **lungs** for oxygenation. * Once the blood has been oxygenated in the **lungs**, it flows back to the **heart** through the **pulmonary vein**, which then goes to the **left atrium**. * The blood then goes to the **left ventricle**, which pumps it to the **aorta**, the main artery of the body that carries oxygenated blood from the heart to all the body parts. * The **aorta** branches into smaller arteries and capillaries. 3. Give three differences between **arteries** and **veins**. | Feature | Arteries | Veins | |-------------|-------------|---------------| | Walls | Thick and elastic | Thinner and less elastic | | Blood flow | High pressure | Low pressure | | Blood flow direction | From heart to organs | From organs to heart | 4. Draw a well-labeled diagram of the human **excretory system**. * The diagram shows the **kidneys**, which are bean-shaped organs that filter waste products from the blood. * The **ureters** are two tubes that transport urine from the kidneys to the **urinary bladder**, where it is temporarily stored. * The **urethra** is a tube that carries urine from the **urinary bladder** out of the body. * The **renal artery** supplies blood to the kidneys, and the **renal vein** carries blood from the kidneys back to the heart. 5. How does transport of food and water take place in plants? * **Transport of Food:** Food prepared by the **leaves** is transported to all parts of a plant by **phloem** in different directions in the plants. * **Transport of Water:** Water and minerals absorbed by the **root hairs** are transported upwards by **xylem vessels**. The **xylem vessels** form a continuous channel from the **root** to the **leaves**. In vessels, water moves by **suction pressure** created by **transpiration** from the **leaves**.