The functional connection between two bones is called a: MCQ with Answer and Explanation

Explanation:
Innate (natural) immunity is the non-specific defense mechanism present from birth, including physical barriers like skin and chemical barriers like stomach acid. Acquired (adaptive) immunity is highly specific and develops after the body is exposed to a specific pathogen or antigen, involving the production of antibodies and memory cells. Vaccines provide artificial immunity (specifically, artificial active immunity), not natural immunity, which is acquired through actual infection or from mother to child. Thus, statements 1 and 2 are correct.

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.

Explanation:
Leucoplasts are colourless plastids that store nutrients: amyloplasts store starch, elaioplasts store lipids, aleuroplasts store proteins. Chloroplasts contain chlorophyll for photosynthesis, chromoplasts give yellow/orange colour (carotenoids), etioplasts are undeveloped chloroplasts in dark-grown plants. Amyloplasts are abundant in roots and tubers like potato.