Practice MCQ Questions and answers on Biology-GK

Ciliary muscles help in changing the focal length of the eye lens.

The eustachian tube is a canal that connects the middle ear to the nasopharynx, which consists of the upper throat and the back of the nasal cavity. It controls the pressure within the middle ear, making it equal with the air pressure outside the body.

Glomerulus and Bowman's capsule constitute Malpighian tubule.

The secretion of renin is stimulated by the following three factors: When a fall in arterial blood pressure is detected by pressure sensitive receptors (baroreceptors) in the arterial vessels. When a decrease in sodium chloride (salt) is detected in the kidney by the macula densa in the juxtaglomerular apparatus.

The kidneys are bean-shaped organs that serve several excretory roles apart from the essential regulatory roles in mammals. They remove from the blood the nitrogenous wastes such as urea, as well as salts and excess water, and excrete them in the form of urine. In producing urine, the kidneys excrete nitrogenous wastes such as urea and ammonium.

Excretory system consists of specialized structures and capillary networks that assist in the excretory process. The human excretory system includes the kidneys and their functional unit, the nephron.

When your kidneys fail, dialysis keeps your body in balance by: removing waste, salt and extra water to prevent them from building up in the body, keeping a safe level of certain chemicals in your blood, such as potassium, sodium and bicarbonate and helping to control blood pressure.

Excretion is best described as the removal of metabolic wastes from a cell.

Islets of Langerhans are islands of endocrine cells scattered throughout the pancreas.

Filtration of blood occur in Bowmen's capsule.