Structural Organisation in Animals Test - 6

Spleen is the largest single mass of lymphatic tissue in body. Blood formation in foetus and newly born child takes place in spleen.

In adults, both WBC and RBC are formed in the bone marrow that is located in long bones such as thighs.

Mature erythrocytes or red blood corpuscles cannot utilize glucose because these cells lack mitochondria as well as nucleus. Though glycolysis or glucose breakdown occurs in the cytoplasm, the final breakdown of pyruvate takes place inside mitochondria. Also the electron transport chain is located inside mitochondria. Hence presence of mitochondria is essential for a cell to utilize glucose and release energy.

The matrix of bone and cartilage differ by the presence of haversian canal that makes bone hard and stiff. On the other hand, cartilage are flexible.

Ciliated columnar epithelium cells in human occur in bronchioles and fallopian tube. They contain small hair like cilia on free surface. This helps to move egg in to fallopian tube. In bronchioles it helps to move mucus or dust particles.

Whales can live in cold water as they have thick coat of blubber. Blubber help in providing insulating coat beneath the skin that prevents loss of heat from the body.

Nerve fibres in the CNS can regenerate after injury due to presence of neurilemma. They are the are outermost nucleated cytoplasmic layer of schwann cells that surrounds the axon of the neuron.

Platelets are little piece of blood cells that help wound healing and prevent bleeding by forming blood clot. It is formed from the megakaryocytes.

A Barr body appears as a small drumstick-like projection on one of the lobes of some neutrophils in females. A Barr body is the inactive X chromosome in a female somatic cell.

Jelly like connective tissue is associated with the umbilical cord. It is flexible cord like structure containing blood vessels and attaching a human fetus to the placenta during gestation.