Practice MCQ Questions and answers on Biology-GK

Cellular respiratory centre is the mitochondria.

The primary root, or radicle, is the first organ to appear when a seed germinates. It grows downward into the soil, anchoring the seedling. In gymnosperms and dicotyledons (angiosperms with two seed leaves), the radicle becomes a taproot.

Nucellus is the wall of megasporangium and the part of ovule in which embryo sac develops. Nucellus provide nutrition to the growing embryo and also protects the embryo.
Chalaza is the portion of ovule which is opposite to the region of attachment of nucellus, integuments and funicle.
Micropyle is a small opening covered by the integuments and it is the site of entry of pollen tube during fertilisation.
Hilum is a structure by which the body of ovule is attached to the funicle.
So, the correct answer is D.

The seeds which contain abundant glyoxysomes are germinating seeds.

Skin is an example of epithelial tissue.

Epidermis varies in thickness throughout the body depending mainly on frictional forces and is thickest on the palms of the hands and soles of the feet, and thinnest in the face (eyelids) and genitalia.

Keratinocytes make keratin, a type of protein that's a basic component of hair, skin, and nails. Keratin in the skin's outer layer helps create a protective barrier.

The actual skin color of different humans is affected by many substances, although the single most important substance is the pigment melanin. Melanin is produced within the skin in cells called melanocytes and it is the main determinant of the skin color of darker-skin humans.

Body organs aren't all internal like the brain or the heart. There's one we wear on the outside. Skin is our largest organ—adults carry some 8 pounds (3.6 kilograms) and 22 square feet (2 square meters) of it.

Dermatology is the branch of science which deals with the study of skin.