Science M.C.Q

Digestion of food starts in mouth by salivary amylase. From here it enters into the stomach via oesophagus. Gastric juice of stomach digests the protein part of food. Pancreatic amylase, trypsin and lipase as well as intestinal peptidases and maltase carry out the final chemical digestion of food in small intestine. The simpler substances formed by chemical digestion are then absorbed by small intestinal villi.

The main excretory unit in the human excretory system is called nephron. It produces urine and maintains the homeostasis of the body.
 

This is because herbivores mainly eat plants. Plants contain cellulose, which is difficult to digest.
Hence, they have the longest small intestine.

White blood cells make chemicals known as antibodies that help to fight against infection and protect the body from foreign particles.

All of them are saprotrophs. In saprotrophic mode of nutrition, food material is broken down outside the body and absorbed.

During blood circulation, blood passes through the kidneys. This blood contains both useful and waste materials. The kidneys filter the wastes from the blood and produce urine. From the kidneys, the urine goes into the urinary bladder through two narrow tubes called ureters. The urinary bladder stores the urine until it is forced out of the body, through an opening known as the urethra.

Stomata are the tiny pores present at the leaf surface. Each stomatal pore is surrounded by two guard cells that assist in stomatal opening driven by turgidity of guard cells. When water flows in guard cells from epidermal cells, guard cells become turgid and stomata are opened. Removal of water from guard cells makes them flaccid and stomata are closed.
The only epidermal cells with unevenly thickened walls and chloroplasts are the guard cells; they are kidney shaped in dicots and dumbell shaped in monocots.

Water absorption through roots can be increased by keeping the potted plants under the fan.

Anaerobic respiration takes place in cytoplasm.

The process of digestion begins in the mouth with the help of the enzymes present in the saliva.

There are two types of capillaries: true capillaries, which branch from arterioles and provide exchange between tissue and the capillary blood, and metarterioles, found only in the mesenteric circulation. They are short vessels that directly connect the arterioles and venules at opposite ends of the beds.

Veins transport deoxygenated blood from various organs of the body towards the heart.
Only pulmonary vein carries the oxygenated blood from the lungs to the heart.

In hemodialysis, a dialysis machine and a special filter called an artificial kidney, or a dialyzer.

Red blood cells do not have nuclei.

Break down of pyruvate using oxygen, i.e., aerobic respiration takes place in the mitochondria. Lactic acid is produced in the muscle from the metabolism of carbohydrate in the cells. When muscles work hard.

Amoebae obtain food by the process called phagocytosis, which means cell feeding.

Mucus protects the inner lining of the stomach from erosion, which can be caused by hydrochloric acid.

Trypsin completes the digestion of protein. Lipase digests emulsified fat to convert it into fatty acids and glycerol.

The device used for measuring blood pressure is called sphygmomanometer.

Carbohydrates are digested by amylases that are present in the saliva and the pancreatic juice.

Xylem is also responsible for providing mechanical strength to the plant and tissue. The chief role of xylem is to transport water and water soluble nutrients from roots to all the parts of the plant. and it also provides support.

Autotrophs obtain the required carbon and energy requirements from carbon dioxide and Sunlight. They combine carbon dioxide and water to form carbohydrates. The main photosynthetic pigment is chlorophyll, which helps to trap the Sunlight to carry out the light reaction of photosynthesis to synthesise carbohydrates.
Since autotrophs are the only organisms that can fix the atmospheric carbon dioxide into organic compounds, these organisms occupy first trophic level in food chain and serve as a source of food and energy for organisms of higher trophic levels.

The autotrophs, like plants, store energy in the form of starch.