Science M.C.Q

During photosynthesis, the water molecule is split into hydrogen and oxygen.

Pancreatic juice has the enzymes amylase for the digestion of carbohydrates, trypsin for the digestion of proteins and lipase for the digestion of emulsified fats.

Platelets release chemicals responsible for blood clotting at the site of a cut or a wound. These chemicals help in the coagulation of blood. The main function of the platelets is to form clot and prevent bleeding.

In a plant, phloem carries substances (food) upwards as well as downwards.

Yeast can live without the oxygen present in the air. This is because it obtains energy by the process of anaerobic respiration.

Alveoli are the pouch - like air sacs at the end of the small bronchioles. The walls of alveoli are very thin. Also, they are surrounded by very thin blood capillaries. It is in the alveoli that the gaseous exchange takes place.

Photosynthesis involves the conversion of light energy into chemical energy by chlorophy ll. In this process, carbon dioxide is reduced to carbohydrates.

Air pressure around our ears decreases.

The largest amount of nitrogen is excreted from a mammalian body as urine.

Trypsin and lipase are enzymes present in the pancreatic juice that digest proteins and emulsified fats, respectively.

The translocation (transport of food) in phloem takes place by utilising the energy stored in the ATP molecules. It takes place in the sieve tubes with the help of adjacent companion cells, both in upward and downward direction.

At high altitude, the atmospheric pressure of oxygen is low. As a result, the number of red blood cells in the body cannot meet the cell's demands for oxygen.
Therefore, the body increases its red blood cell count in order to supply more oxygen to the body cells, even with less oxygen in the atmosphere.
Hence, people living on very high mountains have more red corpuscles in their blood than those living in plains.

Pepsin is secreted by the stomach and trypsin is secreted by the pancreas.

The process of removing wastes (urea) from the blood using a kidney machine is known as dialysis.

when carrying out the starch test, it is important to remove the chlorophy ll by boiling the leaf in alcohol. This is done because the green colour of the chlorophy ll interferes with the iodine test.

The aquatic animals like fish have gills as their respiratory organs. Gills extract oxygen dissolved in water and take away carbon-dioxide from the body. On the other hand, cow, frog and fox, breathe through lungs.

During a marathon, most of the energy in our muscles is produced through aerobic respiration, while anaerobic respiration provides some extra energy needed under these conditions. The anaerobic respiration by the muscles brings about partial breakdown of glucose to form lactic acid. The accumulation of lactic acid in the muscles causes muscle cramps.

Snake is a reptile and has a double circulation in a three - chambered heart. Pisces (e.g. fish) has a single circulation in a two chambered heart, while mammals (e.g. deer) and birds (e.g. sparrow) have a double circulation in a four-chambered heart.

Bile is secreted by the liver and stored in the gall bladder till required.

Plants cannot absorb atmospheric nitrogen. Plants can uptake nitrogen in the form of nitrates and nitrites only

Mushroom obtains its food from decaying organic materials like rotten wood.
Thus, it has a saprophytic mode of nutrition.

The digestion of food, i.e. carbohydrates, fats and proteins, completes in the small intestine.

Salivary amylase digests carbohydrates. Starch is a carbohydrate, which is digested and broken down into sugars by the salivary amylase in the buccal cavity.

Heterotrophs cannot synthesis their food.

Plasmodium is a microbial parasite that has a parasitic mode of nutrition.

Internal respiration may be defined as the oxidation of food substances to release energy.

Sieve plates do not constitute blood. They are a part of phloem.

In woody stems, the bark (outer covering of the stem) has lenticels for gaseous exchange.

The correct sequence of air passage during inhalation is as follows:
Nostrils → Nasal chambers → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli.

Small intestine receives bile from the liver, which is temporarily stored in the gall bladder.

Prawn is an aquatic animal that respires through gills. Insects such as grasshopper, mosquito and cockroach respire through tracheae.

Lizard is a reptile and it has a three-chambered heart. Birds (e.g. Pigeon) and mammals (e.g. lion) have a four - chambered heart, while Pisces (e.g. fish) have a two - chambered heart.

The correct sequence of the parts as they occur in the human alimentary canal is given below.
Mouth → Oesophagus → Stomach → Small intestine → Large intestine.

Lime water turns milky due to the presence of carbon-dioxide in the exhaled air.

Movement of molecules takes place among cells.

Dialysis is the process of removing wastes using an artificial kidney.
Hence, if a patient is out on dialysis, he is most likely suffering from a severe ailment of excretory system. It is because kidneys are a part of human excretory system and in case of kidney failure, to remove the accumulated wastes from the body, blood is filtered periodically through an artificial kidney.

The process of carrying food from the leaves to other parts of a plant is called translocation.

Pulmonary vein carries oxygenated blood (clean blood) from the lungs into the heart.

Ventricles pump oxygenated blood from the heart to the entire body.

Urea is not reabsorbed into the blood capillaries that surround the tubule of a nephron. However, glucose, amino acid and water are reabsorbed.

Electric eel respires through gills. Leech and earthworm respire through their skin.

Xylem transports water and minerals from the soil via the roots to the rest of the plant body.

Pulmonary vein carries the oxygen rich blood from the lungs to the heart.

The digestion of food begins in the mouth by the action of salivary amylase.

In autotrophic mode of nutrition, green plants that have chlorophy ll, make food from carbon-dioxide and water in the presence of sunlight.

Liver secretes the greenish yellow liquid called bile.

Sieve tube, which forms the phloem, are living cells containing cytoplasm but no nucleus.