Box 1- 4/6
boxes 2-4 answer is 1/6 for all of them
Answer: The water in the earth is older than earth itself.The water inside earth came out as steam from volcanic vents and the clouds rained down water..Comets also contain lot of water ice.Early period of solar system large amount of comets and asteroids hit the earth They also brought lot of water.
Explanation:
The genetic code is carried out by the Deoxyribonucleus acid DNA molecule in most organisms. Most of the viruses have RNA as their genetic material which codes genetic information.
Answer:
There are three main types of blood vessels:
1)Artery ---
i) It is a blood vessel having a thick wall.
ii) It carries blood from the heart to different parts of the body.
iii) On regulatory demand of the body it can dilate or constrict.
iv) It doesn't contain any valve.
v) All arteries carry oxygenated blood except the pulmonary artery.
2)Vein ---
i) It is a blood vessel having a thin wall.
ii) It brings blood from different parts to the heart.
iii) It can't dilate or constrict under normal conditions.
iv) It contains valves that allow the blood to flow in one direction towards the heart.
v) All veins carry deoxygenated blood except the pulmonary vein.
3)Capillary ---
i) It is a very narrow blood vessel that has very thin walls.
ii) It forms a network throughout the body in all living cells connecting arteries to veins.
iii) It can dilate or constrict according to the requirement of tissue.
iv) It doesn't have any valve.
v) It contains mixed blood as it connects arteries and veins
