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.

Because autotrophs convert carbon dioxide and water into carbohydrates in the PRESENCE of sunlight.

The excretory system of human beings includes a pair of kidneys, a pair of ureters, a urinary bladder and a urethra. Kidneys are located in the abdomen, one on either side of the backbone. Urine produced in the kidneys passes through the ureters into the urinary bladder where it is stored until it is released through the urethra. Each kidney has large numbers of these filtration units called nephrons packed close together.

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 of food completed in Small intestine. In large intestine only absorption of water take place. In mouth cavity the digestion starts only. In stomach, the digestion of proteins start in acidic medium with the help of pepsin.

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.

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)

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

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

Valves allow the flow of blood in one direction only.

Amoeba has no fixed place for removing the undigested part of food. When a considerable amount of undigested food collects inside Amoeba, then its cell membrane suddenly ruptures at any place and the undigested food is thrown out the body of Amoeba.

Nephrons are the filtration units of kidneys. It is the structural and functional unit of a kidney and has three functions – filtration, reabsorption and secretion. Urine from the kidney passes through a tube called ureter, that carry urine into the urinary bladder. The urethra is a canal that carries urine from bladder and expels it out of body. Neurons nerve cells and are functional units of nervous system.

The oesophagus carries food to the stomach. When the slightly digested food enters the food pipe, the walls of food pipe start contraction and expansion movements. The contraction and expansion movement of the walls of food pipe is called peristaltic movement. This peristaltic movement of food pipe pushes the slightly digested food into the stomach.

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.

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

Since the blood emerges from the heart under high pressure, the arteries have thick, elastic walls.

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.

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.

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

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 pore to open. Similarly the pore closes if the guard cells shrink.

Nitrogen is an essential element used in the synthesis of proteins and other compounds. This is taken up in the form of inorganic nitrates or nitrites.

Mitochondria are the sites of aerobic respiration in the cells. The breakdown of pyruvate to give carbon dioxide, water and energy takes place in mitochondria.

Aerobic respiration uses oxygen for respiration. It takes place in the mitochondria. After glycolysis, pyruvate (from cytoplasm) enters the mitochondria and is oxidised in a series of reactions, to form considerable amount of energy (ATP), CO2 and H2O.

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.