Class 10 Science Chapter 5 MCQ

Heterotrophs are those organisms which cannot make their own food from inorganic substances like CO2 and water as they do not have chlorophyll to trap solar energy, e.g., all animals, most bacteria and fungi. They depend on other organisms for their food. Autotrophs synthesize their own food through photosynthesis by utilising solar energy. e.g., green plants.

Yeast, mushroom and bread mould are saprophytes. They break down and convert complex organic molecules present in dead and decaying matter into simpler substances outside their body. These simpler substances are then absorbed by them, (i.e., saprotrophic nutrition). Green plants are autotrophic (make their own food through photosynthesis). Amoeba and Paramecium are holozoic (take solid or fluid organic food) and Cuscuta, lice, tapeworm are parasitic (live on food material obtained from the body of host).

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

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.

Fermentation is a form of anaerobic respiration. Pyruvate can be converted into ethanol and CO, in yeast during fermentation. Since this process takes place in the absence of air (oxygen), it is called anaerobic respiration. It takes place in cytoplasm. Break down of pyruvate using oxygen, i.e., aerobic respiration takes place in the mitochondria.

Cells generally does not share the transaction of the particles or molecules.

Organisms which can make their own food from carbon dioxide and water are called autotrophs. Carbon dioxide and water are inorganic substance. So, we can say that, those organisms which can make their own food from the inorganic substances present in the environment are called autotrophs. All the green plants are autotrophs.

Large number of tiny pores called stomata are present on the surface of the leaves of plants. The gaseous exchange as well as transpiration takes place through these pores. The opening and closing of the pore is a function of the guard cells. The guard cells swell when water flows into them, causing the stomatal pores to open. Similarly, the pore closes if the guard cells shrink or losses water in them.

The summary equation of photosynthesis is: 6CO2 + 12H20+ Chlorophyll +Sunlight → C6H12O6 +6CO2 + 6H2O by using. Photosynthesis is a process by which green plants make their own food, e.g., glucose, CO2 and H2O in the presence of sunlight energy and chlorophyll in the presence of. Oxygen gas is released during the process of photosynthesis.

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

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

Alveoli of lungs. The walls of the alveoli contain an extensive network of blood-vessels. When we breathe in, we lift our ribs and flatten our diaphragm, and the chest cavity becomes larger as a result. Because of this, air is sucked into the lungs and fills 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.

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 mucus is secreted in the gastric juice by the glands present in the stomach wall. It helps to protect the wall of stomach from its own secretions of hydrochloric acid. If mucus is not secreted, HCI will cause the erosion of inner lining of stomach leading to ulcer formation. Pepsin acts on proteins in the stomach. Salivary amylase is present in saliva, it acts on starch in the mouth. Bile helps in emulsification of fat in small intestine.

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.

Single circulation is found in fishes. Hippocampus, Exoceotus, Anabas exhibit single circulation of blood because these animals belong to Pisces.

Living things can move by themselves. The plants are fixed in the soil at a place so they cannot move like animals from place to place but the plants can only move parts of their body such as leaves, flowers, roots etc.

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

It is in the alveoli in the lungs where gaseous exchange takes place. The walls of the alveoli are very thin and surrounded by network of very thin blood capillaries. The presence of millions of alveoli in the lungs provides a large area for the exchange of gases.

The whole process of an aerobic respiration take place in the cytoplasm of cells.

When we eat something a fluid called saliva secreted by the salivary glands. The saliva contains an enzyme called salivary amylase that breaks down starch which is a complex molecule to give simple sugar.

Fermentation is a form of anaerobic respiration in which Pyruvate can be converted into ethanol and carbon dioxide by yeast.

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.

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.