In DNA, the base complementary to guanine is: MCQ with Answer and Explanation

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:
Stem bears leaves and reproductive structures. It is positively phototropic (grows towards light). Leaves are the main photosynthetic organs. Roots grow downward.

Explanation:
Folate (B₉) and vitamin B₁₂ are required for DNA synthesis. Deficiency leads to impaired cell division in bone marrow, producing large, immature erythrocytes (megaloblasts), causing megaloblastic anemia. Iron deficiency causes microcytic anemia.