Science M.C.Q

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.

Mitochondria is cell structure is involved in the process of formation of glucose.

Heterotrophs are the organisms that cannot synthesize their own food and depend on available organic/ inorganic compounds to fulfil their energy requirements.
Examples : All animals.

Essentially, the chloroplast is an independent fully functional organelle. Although all the green parts of a plant can carry outphotosynthesis, it mainly occurs in the leaves due to the high abundance of chloroplasts. A chloroplast contains stroma, fluid, and stack of thylakoids called grana.

Alveoli are an important part of the respiratory system whose function it is to exchange oxygen and carbon dioxide molecules to and from the bloodstream.

Consuming high amount of water leads to increased water concentration in blood. As a result, osmotic pressure of the plasma decreases because excess water must be eliminated to maintain normal functioning of the body. Decreased osmotic pressure of the plasma tends to push out excess water from the circulatory system.
Consequently, more volume of urine is produced and the person has frequent urination.

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 deoxygenated blood collected from different body parts is poured into the right auricle. From right auricle it moves to the right ventricle and through the pulmonary artery this is deoxygenated blood is pumped into the lungs where it is oxygenated. Then this oxygenated blood is transported to the left Atrium and then moves to the left ventricle from where it is pumped into the whole body.

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.

Breakdown of pyruvate; under anaerobic condition; takes place in cytoplasm of yeast. Ethanol and carbon dioxide are produced at the end of this reaction.

The air enters through nostrils, passes to pharynx, larynx, trachea and then to alveoli. As soon as the air is inhaled the diaphragm and inter coastal muscles contract meanwhile, there is also the expansion of thoracic muscles which creates enough space for the air to enter into the lungs. The process is opposite in the case of exhalation.

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.
 

Prawn is an aquatic animal that respires through gills. The gills extract oxygen dissolved in water and take away carbon-dioxide from the body.
 

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.
 

Human alimentary canal consists of organs of digestion which are namely, in sequence, mouth, oesophagus, stomach, small intestine, large intestine and anus.

Walls of heart facilitate the pumping action only and have no role in preventing backflow of blood.

Trachea and larynx just serve as passage for air. Exchange of gases takes place in alveoli; where oxygen diffuses into blood and carbon dioxide comes out of blood.

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

The process of movement of water in the plants through xylem and its evaporation through leaves or stem is known as transpiration. Transpiration supplies water for photosynthesis, cools the leaves surface through evaporation, and the transpirational pull helps in transportation of minerals from the roots to the leaves. But it never helps in the translocation of sugars. Translocation is the process of movement of food from the leaves to the different parts of the plant through phloem.

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

Starch makes a dark blue complex with iodine. This is the most often used test to check the presence of starch in something.

The inferior vena cava is a vein. It carries deoxygenated blood from the lower half of the body to the right atrium of the heart. The corresponding vein that carries deoxygenated blood from the upper half of the body is the superior vena cava.

Splitting of water molecule, results in liberation of oxygen and hydrogen.
Hydrogen is utilized for reduction of carbon dioxide so that carbohydrate can be made.