Consider statements about plant biology: 1. Photosynthesis occurs in chloroplasts. 2. Respiration occurs in mitochondria. 3. Transpiration occurs only through roots. Which are correct? MCQ with Answer and Explanation

Explanation:
Phototropism is the directional growth of a plant organ in response to light, typically positive in shoots. Geotropism (gravitropism) is the growth response to gravity, with roots showing positive geotropism (growing down) and shoots negative geotropism (growing up). Thigmotropism is the growth response to touch or physical contact, seen in climbing plants like vines, not water (which is hydrotropism). Thus, statements 1 and 2 are correct.

Explanation:
Prolactin (PRL) is a peptide hormone secreted by the lactotroph cells of the anterior pituitary gland. Its primary and namesake function is to stimulate the development of the mammary glands during pregnancy and to initiate and maintain the production of milk (lactogenesis) after childbirth. While prolactin levels rise significantly during pregnancy, the high levels of estrogen and progesterone inhibit actual milk secretion until after delivery. Suckling by the infant is the primary stimulus for continued prolactin release.

Explanation:
DNA replication is semiconservative and uses DNA polymerase. In eukaryotes, it occurs in the nucleus, not cytoplasm. So statement 3 is incorrect.