Consider statements about the human heart: 1. The left ventricle has the thickest wall. 2. The tricuspid valve is between the left atrium and ventricle. 3. The SA node is the natural pacemaker. Which are correct? MCQ with Answer and Explanation

Explanation:
Beta-carotene is a provitamin A carotenoid, giving orange color; the body can convert it to retinol. Lycopene is red (tomato), xanthophyll yellow, chlorophyll green. Carotenoids are accessory pigments in photosynthesis.

Explanation:
Myopia, or nearsightedness, is a refractive error where distant objects appear blurry, but near objects are clear. It occurs when the eyeball is elongated (axial myopia) or the cornea/lens is too curved (refractive myopia), causing light rays from distant objects to focus in front of the retina instead of directly on it. It is corrected using a concave (diverging) lens. Hypermetropia is the opposite, corrected with a convex lens.

Explanation:
The chorion is the outermost membrane surrounding the embryo. It forms chorionic villi that interdigitate with maternal uterine tissue to form the placenta, facilitating nutrient and gas exchange. The amnion surrounds the embryo, forming a fluid-filled cavity. The yolk sac is involved in early nutrition, allantois forms part of the umbilical cord. The chorion is derived from trophoblast and extraembryonic mesoderm.