Consider statements about ecology: 1. Producers form the first trophic level. 2. Energy flow in an ecosystem is unidirectional. 3. The pyramid of energy can be inverted. Which are correct? MCQ with Answer and Explanation
Consider statements about ecology: 1. Producers form the first trophic level. 2. Energy flow in an ecosystem is unidirectional. 3. The pyramid of energy can be inverted. Which are correct?
A. 2 and 3 only
B. 1 and 3 only
C. 1, 2 and 3
D. 1 and 2 only
Answer: Option D
Solution (By JKExamLibrary)
Green plants (producers) always occupy the first trophic level in a food chain. Energy flow is unidirectional, moving from the sun to producers and then to consumers, never returning to the sun. Due to the 10% law of energy transfer, the pyramid of energy is always upright and can never be inverted. Thus, statements 1 and 2 are correct.
Consider statements about human circulation: 1. Arteries carry oxygenated blood. 2. Veins have valves to prevent backflow. 3. Capillaries have thick walls. Which are correct?
Explanation:
While most arteries carry oxygenated blood, the pulmonary artery carries deoxygenated blood from the heart to the lungs. Veins possess valves along their length to ensure unidirectional blood flow back to the heart against gravity. Capillaries are composed of a single layer of endothelial cells (thin walls) to facilitate the exchange of gases and nutrients. Only statement 2 is universally correct.
Explanation:
Sucrose (table sugar) is a disaccharide composed of glucose and fructose. Glucose and fructose are monosaccharides, glycogen is a polysaccharide. Other disaccharides include maltose and lactose.
Explanation:
Testosterone, secreted by Leydig cells of the testes, is responsible for the development of male secondary sexual characteristics like facial hair, deepening of voice, and muscle growth. Estrogen and progesterone are female hormones.
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