Class 10 – Science Extra Questions – Ch. 5 – Life Processes

Ans: C

Explanation: ATP, or adenosine triphosphate, is the main energy currency of the cell. It stores and releases energy through the breaking and forming of its phosphate bonds, powering various cellular processes such as muscle contraction, nerve impulse propagation, and chemical synthesis. DTP, PDP, and DDT are not primarily involved in cellular energy transfer.
Correct Option: C

Ans: C

Explanation: Mammals primarily eliminate excess nitrogen from their bodies in the form of urea. Urea is a waste product of protein metabolism. Urea is synthesized in the liver and then transported to the kidneys, where it is filtered from the blood and excreted in the urine. While some nitrogenous waste can be lost through sweat and faeces, urine is the most significant route of nitrogen elimination.
Correct Option: C

Ans: C

Explanation: Cobalt chloride paper is a desiccant and acts as a moisture indicator. It is blue when dry and turns pink in the presence of water vapor. Transpiration is the process by which plants release water vapor from their leaves. When cobalt chloride paper is attached to the underside of a leaf, it absorbs the water vapor released during transpiration, causing it to change color from blue to pink. Option A is incorrect because cobalt chloride does not react with chlorophyll. Option B is incorrect as pressure from the clipper does not cause the color change. Option D is incorrect because the color change is due to moisture, not the green color of the leaf itself.
Correct Option: C

Ans: C

Explanation: The nephron is the functional unit of the kidney. It begins with a cup-shaped structure called Bowman’s capsule. Within Bowman’s capsule is a network of capillaries known as the glomerulus, where filtration of blood occurs. Option A is incorrect because an ampulla is a dilated portion of a tube, not typically found at the beginning of a nephron. Option B is incorrect because the glomerulus is contained within Bowman’s capsule, not the other way around, and it names the contents before the structure. Option D is incorrect because Bowman’s capsule is the structure, and the glomerulus is within it.
Correct Option: C

Ans: C

Explanation: During strenuous exercise, oxygen supply to muscle cells can be limited. In the absence of sufficient oxygen, muscle cells resort to anaerobic respiration. The first step of both aerobic and anaerobic respiration is glycolysis, which converts glucose into pyruvic acid. If oxygen is not available, pyruvic acid is then converted into lactic acid through a process called lactic acid fermentation. The accumulation of lactic acid in muscle cells leads to a decrease in pH, which can interfere with enzyme function and ultimately contribute to muscle fatigue. Acetyl-CoA is an intermediate in aerobic respiration. Carbon dioxide is a product of aerobic respiration, not anaerobic respiration in human muscle cells.
Correct Option: C

Ans: A

Explanation: Photosynthesis is the process by which green plants and some other organisms use sunlight to synthesize foods with the help of chlorophyll pigment. During this process, plants take in carbon dioxide from the atmosphere through their stomata and use sunlight and water to convert it into glucose (sugar) for energy. Oxygen is released as a byproduct of this reaction.
Correct Option: A

Ans: B

Explanation: Tracheae are a system of air-filled tubes found in many insects and some other arthropods that facilitate gas exchange. Grasshoppers, mosquitoes, and cockroaches are all insects and respire using tracheae. Prawns, on the other hand, are crustaceans and breathe using gills, which are specialized organs for extracting dissolved oxygen from water.
Correct Option: B

Ans: D

Explanation: Plants are autotrophs, meaning they produce their own food through photosynthesis. Photosynthesis converts light energy into chemical energy stored in glucose. While plants do respire to break down glucose for ATP, the net energy expenditure is lower than in animals because they are also producers. Animals, on the other hand, are heterotrophs and must consume other organisms for energy. They also have high energy demands for processes like muscle contraction for movement, which plants generally lack. Active transport of nutrients is a cellular process in both plants and animals and doesn’t inherently explain the *relatively low* energy requirements of plants compared to animals. Therefore, the ability to produce their own food through photosynthesis is the primary reason for their lower energy requirements.
Correct Option: D

Ans: A

Explanation: Organisms that feed on dead and decaying organic matter are called decomposers or saprophytes. Mushrooms are fungi, and fungi are primary decomposers in ecosystems. They break down dead plants and animals, releasing nutrients back into the soil. Malarial parasites are protozoa that live inside red blood cells of the host and feed on hemoglobin, causing malaria. Leeches are annelid worms that are often parasitic, feeding on the blood of other animals. Lice are small insects that are ectoparasites, feeding on blood or skin cells of their hosts. Therefore, only mushrooms fit the description of obtaining nutrients by feeding on dead and decaying organic matter.
Correct Option: A

Ans: C

Explanation: A four-chambered heart completely separates oxygenated and deoxygenated blood. This means that oxygen-rich blood returning from the lungs is pumped directly to the body, and oxygen-poor blood returning from the body is pumped directly to the lungs for reoxygenation. In contrast, a three-chambered heart has some mixing of oxygenated and deoxygenated blood, making oxygen delivery less efficient. This efficiency in oxygen delivery in four-chambered hearts supports higher metabolic rates. Option A is incorrect because it suggests mixing, which is what a four-chambered heart prevents. Option B, while indirectly related to overall health, isn’t the primary advantage of chamber separation. Option D is not a direct or guaranteed consequence of having four chambers; blood pressure is regulated by other factors as well.
Correct Option: C