Biology MCQs

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The Islets of Langerhans are the endocrine cells of the pancreas that produce and secrete hormones such as insulin and glucagon into the bloodstream. The pancreatic hormones, insulin and glucagon, work together to maintain the proper level of sugar (glucose) in the blood.

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The chalaza is a structure inside bird and reptile eggs and plant ovules. It attaches or suspends the yolk or nucellus within the larger structure. It represents the basal part of the ovule.

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The larynx is another name for the voice box. It’s a tube about 2 inches (5cm) long in adults. It sits above the windpipe (trachea) in the neck and in front of the food pipe.

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Vitamin E is known as anti-sterility vitamin or fertility vitamin. It is chemically called as tocopherol. Vitamin E deficiency occurs rarely in adults. Much like vitamin C, vitamin E is another powerful anti-oxidant. Vitamin E is used during testosterone synthesis. Sperm production or spermatogenesis requires vitamin E as well as zinc. Following symptoms have been associated with vitamin E deficiency in humans:

• Muscular weakness & dystrophy, nocturnal muscle cramps
• Neurological disorders
• Degeneration of liver (hepatic necrosis)
• Shortened life-span of RBCs

Notes:
Pasteurization is the process of heating milk up and then quickly cooling it down to eliminate certain bacteria and all other microorganisms. More common is heating milk up to at least 161.6 degrees Fahrenheit for 15 seconds. There are following methods that are most commonly used:
• High Temperature, Short Time (HTST) method – This method requires that the milk be held at 161 degrees for 16 seconds.
• Ultra-Pasteurization (UP) – This is the type of pasteurization that you will most commonly see on cartons of milk, half-and-half and heavy cream.

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Under suitable conditions, a single cell grows into a colony of cells on agar medium. The resulting population of genetically identical cells derived from a single parent cell is called a clone.

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The guinea pig or domestic guinea pig also known as cavy or domestic cavy, is a species of rodent belonging to the family Caviidae and the genus Cavia.

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Spiders, mites, scorpions, and several related groups are not insects, but belong to the arthropod class Arachnida. About 15 families of spiders are frequently encountered in crops, where they provide benefit as natural control agents.

Notes:
The corpus luteum is a hormone-secreting structure that forms in the ovary after an egg has been released during ovulation. It is made up of cells that were part of the follicle that contained the egg, and it produces the hormones progesterone and estrogen, which help to support pregnancy. The corpus luteum is important for maintaining the lining of the uterus and preparing the body for pregnancy. If pregnancy does not occur, the corpus luteum will break down and be absorbed by the body.

Notes:
The order Acarina (class Arachnida) includes mites and ticks. Members of this order differ from other arachnids in that the body is not segmented, and the cephalothorax and abdomen are combined into one body region. Larval mites and ticks have three pairs of legs, whereas nymphs and adults have four pairs.