The phenomenon of a plant flowering in response to the length of day is called:
A. Phototropism
B. Chemotropism
C. Geotropism
D. Photoperiodism
Answer: Option D
Solution (By JKExamLibrary)
Photoperiodism is the response of plants to the relative lengths of day and night, influencing flowering. Short-day plants (e.g., poinsettia) flower when day length is less than a critical period; long-day plants (e.g., spinach) flower when days are longer. Phototropism is growth towards light, geotropism to gravity, chemotropism to chemicals.
Consider statements about animal husbandry: 1. Artificial insemination improves cattle breeds. 2. Multiple Ovulation Embryo Transfer is used in poultry. 3. Crossbreeding combines traits of two breeds. Which are correct?
Explanation:
Artificial insemination allows the use of superior bull semen to improve cattle genetics widely. Multiple Ovulation Embryo Transfer (MOET) is a technique used in cattle and other mammals to increase herd improvement rates, not in poultry (which uses hatching eggs). Crossbreeding involves mating animals of different breeds to combine desirable traits and exploit hybrid vigor. Thus, statements 1 and 3 are correct.
Explanation:
Neurulation involves the folding of the neural plate to form the neural tube, which becomes the brain and spinal cord. Gastrulation forms germ layers.
Consider the following statements about DNA replication:
1. It is semiconservative.
2. It requires DNA polymerase.
3. It occurs in the cytoplasm of eukaryotic cells.
Which of the above is/are correct?
Explanation:
DNA replication is semiconservative and uses DNA polymerase. In eukaryotes, it occurs in the nucleus, not cytoplasm. So statement 3 is incorrect.
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