Deoxygenated (without oxygen) blood flows from the right atrium to the right ventricle and then, right ventricle pumps blood into the pulmonary artery. The pulmonary artery carries deoxygenated blood to the lungs, where it is supplied with fresh oxygen and carbon dioxide is removed.

The loss of water in the form of vapours from the aerial parts of a plant is known as transpiration. It helps in (1) absorption and upward movement of water and minerals dissolved in it from roots to leaves (2) temperature regulation

Phloem transports products of photosynthesis (sugar and food) from the leaves where they are synthesised to other parts of the plant.

Veins collect blood from different organs and bring it back to the heart. They do not require thick walls as found in arteries because the blood is not under pressure. However, veins have valves that ensure that the blood flows only in one direction towards the heart and thus, prevent back flow of blood.

Inferior vena cava brings blood from lower half of the body. Superior vena cava brings blood from upper half of the body. Both of these large veins join at the right atrium of the heart. Thus, (2) is incorrect and (1) is correct.

Blood has platelet cells which help in clotting of blood at the points of injury. Blood clotting is a complex mechanism.

The pulmonary artery carries de-oxygenated blood to the lungs, where it is supplied with fresh oxygen, and carbon-dioxide is removed. The blood, which is now rich in oxygen, returns to the heart through the pulmonary veins.

For plants, soil is the richest natural source of raw materials like nitrogen, phosphorus and other minerals. The absorption of these substances occurs through roots. Chemical fertilisers are synthetic-chemical substances used to enrich soil to promote plant growth. They are not natural sources of minerals for plants. Air is natural but does not contain minerals. Water contains minerals, salts or gases. But it is not the richest source of minerals for plants.

On reaching the organ or tissue, the artery divides into smaller and smaller vessels to bring the blood in contact with all the individual cells. The walls of the small vessels are one-cell thick and are called capillaries. Exchange of material between the blood and surrounding cells takes place across this thin wall. The capillaries then join to form veins that take blood away from organ or tissue.

The blood vessels that carry blood from different regions of the body towards the heart are called veins. The veins are usually thin walled with wide lumen. There are sets of semilunar valves inside the veins, which regulate the unidirectional flow of the blood. On the other hand arteries are the blood vessels that carry blood from the heart to different regions of the body. They are usually thick walled with narrow lumen.

Heart is divided into two halves: the right and left sides of the heart. The right side of the heart pumps deoxygenated blood to the lungs whereas the left side of the heart pumps oxygenated blood to the body. The right atrium pumps blood to right ventricle and the right ventricle pumps blood into the pulmonary artery. The pulmonary artery carries this deoxygenated blood to the lungs where it takes up oxygen and eliminates carbon dioxide.

Phloem - Phloem transports products of photosynthesis (sugar and food) from the leaves where they are synthesized to other parts of the plant. It is made up of 4 types of elements - sieve tubes, companion cells, phloem fibres and the phloem parenchyma. Xylem transports water and minerals obtained through soil. Xylem consists of tracheids, vessels, xylem parenchyma and xylem fibres. Tracheids and vessels are tubular structures. These allow them to transport water and minerals vertically. The parenchyma stores food and helps in sideways conduction of water. Fibres are mainly supportive in function. Both phloem and xylem are known as conducting tissues. Therefore, water conducting channel in plants is xylem. Stomata are the tiny pores present on the surface of leaves. Exchange of gases takes place through these pores for the process of photosynthesis. These openings are surrounded by guard cells which, through changes in their size and shape, alter the size of stomatal openings and thus regulate the gas exchange. During transpiration, large amounts of water can be lost through these stomata. The plant closes its pores when it does not require CO₂ for photosynthesis. The opening and closing of stomata is a function of guard cells. The guard cells swell when water flows through them causing the stomatal pore to open. Similarly, the pore closes if the guard cells shrink. Lenticels are the pores on the plant stem through which gaseous exchange takes place.

There are four valves in the heart, which prevent blood from flowing backward in the heart. The valves open easily in the direction of blood flow but when the blood pushes the valve in the opposite direction, the valves close. 2 valves = Atrioventricular valves = located between atria and ventricles 2 valves = Semilunar valves = located between ventricles and arteries. Pulmonary valve - Between the right ventricle and pulmonary artery Aortic valve - Between the left ventricle and aorta

Crocodile belongs to class Reptilia. All the members of class Reptilia have a 3-chambered heart. Crocodile is an exception, which possesses 4-chambered heart like mammals and birds.

Oxygenated blood from the lungs comes to thin walled upper chamber of the heart (left atrium). Left atrium is relaxed when it is collecting the oxygenated blood. After that, it contracts, while the next chamber (the left ventricle) expands. So, the blood is moved to left ventricle. If the left ventricle contracts, it pumps the oxygenated blood to different parts of the body.

Fat, potassium and lipids are not the products of photosynthesis.

Vitamin K is necessary for blood clotting. Blood has platelet cells, which help in clotting of blood at the points of injury. Blood clotting is a complex mechanism. Vitamin K plays an important role as it helps in forming an enzyme, which helps in clotting. Dietary sources of vitamin K are fish livers, egg yolks, soyabean and green leafy vegetables.

Oxygenated blood passes from the left atrium into the left ventricle, from where it is pumped out of the heart into the aorta (body's largest artery).

After supplying oxygenated blood to various parts of the body, the blood becomes deoxygenated. This deoxygenated blood is supplied into a large vein known as vena cava, which empties into right atrium or auricle of the heart. 

Blood consists of a fluid medium known as plasma, in which red blood cells (RBCs), white blood cells (WBCs) and platelets are suspended. Plasma transports food (nutrients), carbon dioxide and nitrogenous wastes in dissolved form. Potassium (K) - Mineral nutrients are supplied by plasma. K helps in contraction of muscles and in sending nerve impulse. Alcohol - Alcohol is also transported by blood plasma. BAC (Blood Alcohol Concentration) is the concentration of alcohol in a person's blood. Alcohol is quickly absorbed in the blood. High intake of alcohol decreases the level of beta-carotene in plasma. (Beta-carotene is used for formation of vitamin A.)