Class 10 Science Chapter 5 MCQ

It is incorrect as; autotrophs can convert carbon dioxide and water into carbohydrates only in the presence of sunlight. The autotrophs contain the green pigment called chlorophyll which is capable of trapping sun energy. This trapped energy is utilised by them to make food by combining inorganic materials like CO2 and H2O by the process of photosynthesis. The food that is not used immediately, is stored in the form of starch. These autotrophs constitute the first trophic level in food chains.

Food comes first in Mouth and then moves through Oesophagus and stomach → small intestine → large intestine.

The correct path of urine is Kidney → Ureters → Urinary bladder → Urethra. The urine formed in each kidney eventually enters a long tube, the ureter, which connects the kidneys with the urinary bladder. Urine is stored in the urinary bladder until the pressure of the expanded bladder leads to the urge, to pass it out through the Urethra.

Non-living things which are not alive cannot move by themselves. For example, a stone is a non-living thing which cannot move by itself from one place to another or show any other type of movement. We will have to move it by applying force from outside.

Energy is required by an organism even during sleep because when we are asleep a number of biological processes keep on occurring in the body which require energy. Our heart beats non-stop even when we are asleep to pump blood throughout the body. And this beating of heart requires energy. Thus, the working of heart requires are continuous supply of energy.

The digestion in stomach is taken care of by the gastric glands present in the wall of the stomach. These release hydrochloric acid, a protein digesting enzyme called pepsin and mucus. The mucus protects the inner lining of the stomach from the action of the acid under normal conditions.

The small intestine is the site of the complete digestion of carbohydrates, proteins and fats. It receives Bile juice, the secretions of the liver and also pancreatic juice from pancreas for this purpose.

Green plants are autotrophic and synthesize their own food by the process of photosynthesis. The process of photosynthesis can be represented as: 6CO2 + 6 H2O + Sunlight + Chlorophyll → C6H12O6 + 6O2 (releases)

Carbon dioxide is used in photosynthesis for the products on of food. The oxidation of carbon compounds occurs in respiration.

Here, all the statements are correct. Hence your answer will be option [D].

Lime water turns milky due to presence of carbon dioxide. The reaction of lime water and carbon dioxide forms calcium carbonate which is insoluble in water and makes lime water milky.

Nostrils → pharynx → larynx → trachea → alveoli. The alveoli provide a surface where the exchange of gases can take place.

Chloroplast are the organelles in the cells of green plants which contain chlorophyll and where photosynthesis take place. Thus, photosynthesis occurs in the organelles called the chloroplast present in the photosynthetic cell or mesophyll cell of green plants. In the other words, the site of photosynthesis in cell of the leaf are chloroplast. Chloroplast can be seen easily by using a light microscope.

Oxygen liberated during photosynthesis comes from water. The following events occur during photosynthesis (i) Absorption of light energy by chlorophyll. (ii) Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen. (iii) Reduction of carbon dioxide to carbohydrates, which is used as food for plants

The human saliva contains an enzyme called salivary amylase, which breaks down the starch present in food into sugar. The digestion of starch (carbohydrates) begins in the mouth. In case, saliva is lacking, it will affect the break-down of starch. The protein digestion begins in the stomach by the enzyme pepsin and completes in small intestine by enzyme trypsin, chymotrypsin, carboxypeptidases, aminopeptidases and dipeptidases. The fats are broken down into small particles by bile in small intestine and then broken-down fatty acids and glycerol by lipases present in pancreatic juice. Absorption of vitamins takes place in the small intestine.

Pisces have only two chambers to their hearts, and the blood is pumped to the gills, is oxygenated there, and passes directly to the rest of the body. Thus, blood goes only once through the heart in the fish during one cycle of passage through the body.

The following events occur in photosynthesis (i) Absorption of light energy by chlorophyll. (ii) Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen. (iii) Reduction of carbon dioxide to carbohydrates.

During the photosynthesis, the following steps take place: (i) Absorption of light energy by chlorophyll. (ii) Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen. (iii) Reduction of carbon dioxide to carbohydrates.

Valves ensure. that blood does not flow backwards when the atria or ventricles contract. Since ventricles have to pump blood into various organs with high pressure, they have thicker walls than atria. The separation of the right side and left side of heart by valve also helps to keep oxygenated and deoxygenated blood from mixing so as to supply high amount of oxygen to the body.

Left ventricle pumps oxygenated blood to different body parts while right ventricle pumps deoxygenated blood to lungs. Whereas right atrium receives deoxygenated blood from different parts of the body while left ventricle pumps oxygenated blood to different parts of the body. Hence, Deoxygenated blood flows through the right side of the heart. Oxygenated blood flows through the left side of the heart.

When there is a lack of oxygen in our muscle cells, another pathway for the break-down of pyruvate is taken. Here the pyruvate is converted into lactic acid which is also a three-carbon molecule. This build-up of lactic acid in our muscles during sudden activity causes cramps.

The air for respiration is drawn into our body through the nostrils, it then goes into nasal passage. From there, air enters into pharynx, larynx, then into the windpipe (or trachea), bronchi, lungs and finally to the alveoli where gaseous exchange takes place.

When we breathe in, we lift our ribs and flatten our diaphragm, the chest cavity becomes larger. Alveoli is balloon like structure which provides a surface where the exchange of gases occurs the walls of alveoli consist of network of blood-vessels. The air is sucked into the lungs to fill the expanded alveoli. The blood brings carbon dioxide from the rest of the body for release into the alveoli. And the oxygen in the alveolar air is taken up by blood in the alveolar blood vessels to be transported to all the cells in the body. In human beings, the respiratory pigment is haemoglobin which has a very high affinity for oxygen. This pigment is present in the red blood corpuscles. The human lungs have millions of air sacs called alveoli whose surface area is many that of the body. These are involved in exchange of gases.

Here, all the statements are correct. Hence your answer will be option [D].

The blue black colour of rice water confirms the presence of starch. No colour change will be seen in case of proteins fats in iodine solution colour, when iodine is added with them. Note: A starch solution on addition of iodine turns blue black in colour.