Which of the following statements about the chloroplast is correct? MCQ with Answer and Explanation

Explanation:
Fossils are the preserved remains or traces of ancient organisms, providing crucial evidence for evolution. Analogous organs (like wings of birds and insects) perform similar functions but have different structural plans and evolutionary origins, indicating convergent evolution. Jean-Baptiste Lamarck proposed the theory of inheritance of acquired characters, while Charles Darwin proposed natural selection. Thus, statements 1 and 2 are correct.

Explanation:
Scoliodon is a cartilaginous fish (Chondrichthyes), possessing a cartilaginous endoskeleton, placoid scales, and ventral mouth. Rohu and Catla are bony fishes (Osteichthyes). Hippocampus is also a bony fish. Chondrichthyes include sharks, rays, and skates. They lack an air bladder and have to swim constantly to avoid sinking.

Explanation:
Calcitonin is produced by the parafollicular (C) cells of the thyroid gland. It lowers blood calcium levels by inhibiting osteoclast activity and promoting calcium deposition in bones. Parathyroid hormone (from parathyroid glands) raises calcium. Adrenal and pituitary glands have other functions.