Class 10 Science Chapter 5 MCQ

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).

The first step is the break-down of glucose, a six-carbon molecule, into a three-carbon molecule called pyruvate. This process takes place in the cytoplasm.

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

The blood leaving the tissues becomes richer in Carbon Dioxide. Because tissues receive the oxygenated blood from arteries and used up the oxygen to take energy and release the carbon dioxide.

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.

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

The solution turned blue-black in colour just because of starch.

Digestion process starts from the mouth where salivary glands are present. Salivary glands produce amyloses. So, amylase is the first enzyme to mix with food. The saliva secreted by the salivary glands in mouth contains this enzyme that breaks down starch. Pepsin is a protein digesting enzyme secreted by the gastric glands present in the stomach wall. The pancreas secretes pancreatic juice in the small intestine. It contains enzymes like trypsin for digesting proteins. Cellulase is an enzyme complex which breaks down cellulose. Most animals, including humans (except ruminants) do not produce cellulase and are therefore unable to use most energy contained in plant material.

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.

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

Valves allow the flow of blood in one direction only.

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 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.

Hippocampus, Exocoetus, Anabas. Because the rate of energy required for the body activities is very low.

Arteries are the vessels which carry blood away from the heart to various organs of the body. Since the blood emerges from the heart under high pressure, the arteries have thick, elastic walls. Veins collect the blood from different organs and bring it back to the heart. They do not thick walls because the blood is no longer under pressure, instead they have valves that ensure that the blood flows in only one direction.

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

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.

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.

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

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.

Carbon dioxide gas turns limewater milky. When air is blown from mouth into test, the lime water turns milky because the air we breathe out has more CO2.

Pancreas secretes pancreatic juice which contain following: Digestive enzymes amylases, lipases, trypsin. Amylase breaks down the starch, trypsin digests the proteins and lipase breaks down the emulsified fats.

The small intestine in human beings is the site of complete digestion of food. It is also the main region for absorption of digested food. However, digestion begins in the mouth cavity, food is further digested in the stomach to form a semi-solid paste. The undigested food from small intestine passes into large intestine that absorb most of the water.