Biology MCQs

Notes:
The skin is the soft outer covering of vertebrates that guards the underlying muscles, bones, ligaments, and internal organs. The cutaneous membrane is the technical term for our skin. The skin’s primary role is to help protect the rest of the body’s tissues and organs from physical damage such as abrasions, chemical damage such as detergents, and biological damage from micro organisms. Our skin is made of three general layers. In order from most superficial to deepest they are the epidermis, dermis, and subcutaneous tissue.

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The process of breaking down large molecules into simpler one in the presence of enzyme is called fermentation. Alcoholic fermentation is a complex biochemical process during which yeasts convert sugars to ethanol, carbon dioxide, and other metabolic byproducts that contribute to the chemical composition and sensorial properties of the fermented foodstuffs.

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Internal fertilization is a mode of reproduction wherein the fusion of male and female gametes (sperm and egg) occurs inside the female body. It’s a common method in terrestrial animals due to the higher survival rate of fertilized eggs within a protected internal environment. Contrastingly, external fertilization takes place outside the female body, often in aquatic environments.

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The phosphate groups on DNA are ionic and charged. Each phosphate group on the DNA backbone has one unit of negative charge (-1). Charged molecules attract water and are hydrophilic. DNA has two hydrophilic polar external backbones made of sugars and phosphate groups joined by ester bonds. Therefore, DNA as nucleic acid is characterized by presence of phosphodiester bond.

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Ascariasis is a disease caused by the parasitic roundworm Ascaris lumbricoides. Infection occurs by eating food or drink contaminated with Ascaris eggs from feces. Ascariasis is most common in places without modern sanitation.

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Pulses are example of dicots since they have two cotyledons (dicot is short for ‘dicotyledon’, and ‘di’ means two). They contain two seeds inside the seed coat. Legumes (a family of plants that includes pluses, beans, peas and lentils) are all examples of dicot seeds.

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Agar, one of the commercial products obtained from Gelidium and Gracilaria are used to grow microbes and in preparations of ice-creams and jellies. The gelling agent in agar is an unbranched polysaccharide obtained from the cell walls of Gelidium and Gracilaria. For commercial purposes, it is derived primarily from Gelidium amansii. In chemical terms, agar is a polymer made up of subunits of the sugar galactose.

Notes:
Chicory powder is made from the root of the chicory plant, Dithorium intybus. The root is dried, roasted, and ground up, to produce a naturally decaffeinated dark brown powder. Chicory’s flavour is similar to that of coffee, although it tastes a bit more roasted and has a sweeter aroma.

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Certain plants which possess the C4 dicarboxylic acid pathway of CO2 fixations show a structural dimorphism of chloroplast structure. Sugarcane is a common example of C4 plant that has dimorphic chloroplast. The mesophyll cells possess chloroplasts with well developed grana whereas the bundle sheath chloroplasts lack the organization of grana (Agranal chloroplasts). The malic acid is transported to the bundle sheath chloroplast (Transportations). Here it is converted to pyruvic acid and CO 2 by NADP+ malic enzyme (Decarboxylation). The pyruvic acid is then transported to mesophyll chloroplasts (Transportation).

Notes:
Light that enters the eye is focused onto the retina at the back of the eye. The retina contains light sensitive cells called rods and cones. The rod and cone cells contain special proteins which absorb light resulting in activation of the cell. The signals generated by the rods and cones of the retina are transmitted to the neurons which form the optic nerve. The signals are then sent to an area of the brain called the visual cortex where the information is processed.