35 questions · auto-graded multiple-choice test.
Autotrophs are the organisms that use light as source of energy, carbon dioxide as chief carbon source and water as electron donor to fix the atmospheric carbon dioxide into organic compounds (carbohydrates). The main photosynthetic pigment chlorophyll a and accessory pigments chl b, chl c and carotenoids etc trap the Sunlight to carry out the light reactions of photosynthesis. The light reaction of photosynthesis produces ATP and reducing agents which in turn serve as energy source to drive the second phase of photosynthesis (dark reactions) during which carbohydrate synthesis takes place.
The carbohydrates which are not immediately consumed by plants are stored as starch (homopolysaccharide of D-glucose).
Glycogen serves as main stored form of carbohydrates in animals.
Chemical digestion of food starts in the mouth. Digestion of starch by salivary amylase takes place in mouth. Oesophagus serves to push the food into stomach only. NO digestion takes place here. Gastric juice of stomach digests the protein part of food. Pancreatic amylase, trypsin and lipase as well as intestinal peptidases and maltase carry out chemical digestion of food in small intestine. The simpler substances formed by chemical digestion are then absorbed small intestinal villi. Large intestine is the organ of water and salts reabsorption from undigested food and elimination of remaining undigested material out of body.
Respiration is the sole source of energy in muscles. During intense physical activity, limited oxygen supply do not support the aerobic respiration and muscles carry out lactic acid fermentation of pyruvate to meet the energy demand.
The examples and the relation of animal group and heart are as,
Fishes have two chambered heart and exhibit single circulation while three chambered heart of amphibian and reptiles and four chambered heart of birds and mammals exhibit double circulation. In given options, C includes all fishes which makes it correct answer.
Aerobic respiration is complete breakdown of glucose into carbon dioxide and water with release of large amount of energy. It occurs in three steps, glycolysis, citric acid cycle and ETC. Glycolysis is breakdown of glucose into pyruvate. It is oxygen independent pathway that occurs in cytoplasm. Aerobic respiration takes place in the mitochondria, using the pyruvate produced via glycolysis. It produces large amounts of energy in t he form of ATP along with carbon dioxide gas and water.
This happens because of single circulation. The deoxygenated blood from all body parts comes to heart and is pumped to the gills where it gets oxygenated. This oxygenated blood is transferred to all body parts from gills.
The left ventricle pumps blood into the aorta which in turn branches and delivers oxygenated blood to the major body regions and organs. The oxygen is consumed in cellular respiration and the carbon dioxide produced during respiration enters into blood.
The anterior vena cava collects deoxygenated blood from the head, chest, and arms and enters the right atrium while the inferior vena cava collects blood from the lower body regions. Both venae cavae pass the deoxygenated blood to the right atrium. Thus, blood from tissues is rich in carbon dioxide.
Deoxygenated blood from right atrium enters right ventricle and pulmonary arteries carry deoxygenated blood from right ventricle to lungs for oxygenation.
Carbon dioxide gas turns lime water milky. Since the exhaled air is carbon dioxide rich, when air is blown from mouth into test tube, the lime water turned milky.
Bile is secreted by liver and is stored in gall bladder from where it enters the small intestine via common duct.
Due to this, nephron is called the functional unit of Kidney.
The correct path of urine is kidney -4 Ureters -4 Urinary bladder Urethra.
Kidneys are the paired organ where urine formation takes place. Small muscular tube, called as ureter, extend from kidneys and carry blood to urinary bladder. The urethra is a small tube that extends from the urinary bladder to an external opening. Hence, option C is the correct sequence.
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.
Breakdown of pyruvate; under anaerobic condition; takes place in cytoplasm of yeast. Ethanol and carbon dioxide are produced at the end of this reaction.
Option $'a\ ’$ shows correct reaction. But option $'c\ ’$ shows correct reaction as well as other important factors of reaction. Option $'b\ ’$ is not a balanced equation. Option $'d\ ’$ shows carbon dioxide among the products; which is wrong.
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.
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.
During inhalation, the air is drawn through the nostrils into nasal passage. From there, air enters into pharynx, larynx, trachea (windpipe), bronchi, lungs and finally to the alveoli.
Digestion of food starts in mouth by salivary amylase. From here it enters into the stomach via oesophagus. Gastric juice of stomach digests the protein part of food. Pancreatic amylase, trypsin and lipase as well as intestinal peptidases and maltase carry out the final chemical digestion of food in small intestine. The simpler substances formed by chemical digestion are then absorbed by small intestinal villi.
All of them are saprotrophs. In saprotrophic mode of nutrition, food material is broken down outside the body and absorbed.
Anaerobic respiration takes place in cytoplasm.
Salivary amylase converts starch into sugar. Digestion of proteins and fats does not take place in mouth, hence options (a) and (c) are incorrect.
Trypsin completes the digestion of protein. Lipase digests emulsified fat to convert it into fatty acids and glycerol.
Autotrophs obtain the required carbon and energy requirements from carbon dioxide and Sunlight. They combine carbon dioxide and water to form carbohydrates. The main photosynthetic pigment is chlorophyll, which helps to trap the Sunlight to carry out the light reaction of photosynthesis to synthesise carbohydrates.
Since autotrophs are the only organisms that can fix the atmospheric carbon dioxide into organic compounds, these organisms occupy first trophic level in food chain and serve as a source of food and energy for organisms of higher trophic levels.