Biology MCQs

Notes:
The excretory system is a collection of organs tasked with removing excess nitrogen and other toxins from the body. Several parts of the body such as sweat glands (excretion of sweat), liver (detoxifies and breaks down chemicals, poisons and other toxins that enter the body), lungs (disposal of carbon dioxide through exhalation) and kidneys (excretion of waste through urinary system) are involved in this process. The spleen also called grave yard of RBC is not considered as an excretory organ.

Notes:
Small intestine is the longest part of the alimentary canal because it is the main organ of absorption and digestion of food. The surface area of the small intestine gets increased because of the presence of villi which gives food plenty of time to break down properly.

Notes:
A pacemaker is a small device that’s placed in the chest or abdomen to help control abnormal heart rhythms. This device uses low-energy electrical pulses to prompt the heart to beat at a normal rate. Pacemakers are used to treat arrhythmias.

Notes:
Cholesterol is defined as a waxy alcohol, fat-like substance that occurs naturally in all areas of the human body. 100-200 mg/dL is considered as normal for the human beings. The total cholesterol counts below 180 mg/dl increase the risk for haemorrhagic stroke; and above 200 mg/dl may be normal and healthy for some people, as the ratio of LDL to HDL cholesterol is considered a more important factor in prediction of disease risk particularly heart disease.

Notes:
The best and a highly recognised natural system of classification was proposed by George Bentham and Sir Joseph Hooker, two great British botanists associated with Royal Botanical Garden at Kew, in their General Plantarum (1862-1883). They classified plants strictly on the basis of a natural scheme. This system is based not only on the characters of the reproductive organs and structural relationship, but all the other important characters are also taken into consideration and the plants are classified according to their related characters.

Notes:
The primary function of the red blood cells, or erythrocytes, is to carry oxygen from the lungs to body tissues and to transfer carbon dioxide from the tissues to the lungs. The RBC is a count of the number of red blood cells per cubic millimeter of blood. Newborns: 4.8 – 7.2 million Adults: (males): 4.6 – 6.0 million

Notes:
Grasshoppers are a group of insects belonging to the suborder Caelifera. They have three main body parts, the head, the thorax and the abdomen. They breathe through a series of holes called ‘spiracles’ which are located along the sides of the body. On grasshoppers, there is a large round disc on the first segment next to the thorax. It is called a tympanum and is the grass-hopper’s ear.

Notes:
Cholesterol is a fatty substance known as a lipid that is vital for the normal functioning of the body. It’s mainly made by the liver, but can also be found in some foods. At normal levels, it is an essential substance for the body. However, if concentrations in the blood get too high, it becomes a silent danger that puts people at risk of heart attack.

Notes:
The pituitary gland also considered as the master gland secretes FSH which further stimulate the secretion of male sex hormone testosterone and in female ovary induces the secretion of oestrogen and progesterone. It also secrete hormones such as lutenizing hormones to ovulation , oxytocin for child birth and prolacting for breast development and milk secretion from mother.

Notes:
The Miller–Urey experiment of 1952 simulated the conditions present on the early Earth, and tested the chemical origin of life under those conditions in a laboratory. The experiment demonstrated how amino acids could be generated in a lab environment from simple compounds subjected to electrical discharges in the early Earth’s atmosphere. The spontaneous creation of amino acids was used in this experiment to explain life’s origin by chemosynthesis as proposed by oparin and later supported by Haldane.