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.

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

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.

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.

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.

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.

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.

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.

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.

Liver secretes the greenish yellow liquid called bile.

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

Lack of oxygen in muscles causes accumulation of lactic acid, due to anaerobic respiration.
Accumulation of lactic acid leads to cramps in the legs of sprinters.

The food is ingested through the mouth. It is then digested in the mouth, the stomach and the small intestine. Then, it is absorbed and assimilated in the small intestine, the reabsorption of water takes place in the large intestine and the undigested waste is egested through the anus.

During anaerobic respiration in human beings, pyruvic acid is converted into lactic acid in the mitochondria of the muscle cells.

b.

No

No

Explanation:
There are two pathways through which anaerobic respiration occurs. In micro - organisms such as yeast and bacteria, the glucose is broken down into ethanol and carbon-dioxide, and releases very little energy. In the other pathway, glucose is broken down into only lactic acid with the release of little energy. This occurs in the muscles during strenuous exercise. Therefore, carbon-dioxide is not always produced during anaerobic respiration.

In the muscle cells that lack oxygen, concentration of lactic acid is increased. This is because, here, anaerobic respiration takes place in which glucose is converted into lactic acid with the release of a small amount of energy.

The digestion of proteins begins in the stomach by pepsin.

In earthworm, the main excretory organs are nephridia. It functions like a kidney.

Rate of breathing in aquatic animals is much faster than terrestrial animals.
This is because a faster rate of breathing provides more oxygen to the aquatic animals.

When guard cells have water, stomatal pores open and when water moves out of the guard cells, these pores close.

Parakeet and Paramecium feed on solid food.
Therefore, they have holozoic mode of nutrition.

Transpiration is the loss of water through the stomata of leaves and other aerial parts of the plants in the form of water vapour. It provides a transpirational pull, which is responsible for the upward movement of water and dissolved minerals from the roots to the leaves through the stem.

Pulse is the expansion of the artery each time the blood is forced into it.

Leech and earthworm breathe only through their moist skin.
Fish breathe through gills, while frogs breathe through lungs and skin.

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.

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.

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

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

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.

Red blood cells do not have nuclei.

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.

The device used for measuring blood pressure is called sphygmomanometer.

Tracheids are the only conducting tissue in non - flowering plants.

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

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