Biology MCQs

Notes:
Seals, Walruses and Sea lions are Mammals belonging to a single taxonomic group ( a clade) called Pinnipedia, which means fin footed. All of them are semi-aquatic marine mammals. They belong to the order Carnivora and their closest living relatives are bears. They are characterized by modification of limbs to flippers. Pinnipeds are mammals with four flippers — one pair in front and one at the back. They are warm-blooded, nurse their young, breathe air and have hair. The sea lion has small, tiny external ear flaps. Seals have no flaps. The front flippers of sea lions are long, have no hair and nails. Seals’ front flippers are short, blunt, covered with hair with nails on the ends. Sea lions can turn their hind flippers forward to move on land but seals cannot do so.

Notes:
Algae is an informal term for a large, diverse group of photosynthetic eukaryotic organisms that are not necessarily closely related, and is thus polyphyletic.

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Any legume plants will help in nitrogen fixation. Beans contain symbiotic bacteria called Rhizobia within nodules in their root systems, producing nitrogen compounds that help the plant to grow and compete with other plants. When the plant dies, the fixed nitrogen is released, making it available to other plants and this helps to fertilize the soil.

Notes:
The retina is a thin membrane which covers the inside back of the eye. Like film in a camera, the retina is the light-sensitive surface where images from the outside world come to a focus.

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The message to the brain form any body part takes the form of nervous impulses. Nerve impulses are mostly electrical signals along the dendrites to produce a nerve impulse or action potential. The action potential is the result of ions moving in and out of the cell.

Notes:
Worms help to increase the amount of air and water that gets into the soil. They break down organic matter, like leaves and grass into things that plants can use. When they eat, they leave behind castings that are a very valuable type of fertilizer. Earthworms are like free farm help.

Notes:
Echinoderm is the common name given to any member of the phylum Echinodermata of marine animals. The adults are recognizable by their radial symmetry, and include such well-known animals as starfish, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies or “stone lilies”.
The sexes are separate except few echinoderm species. There is no sexual dimorphism. Fertilization is external and few forms are viviparous.

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Wolf alpha pairs are usually monogamous with each other, but alpha males have been known to stray with other pack members, especially if they are closely related. Among red foxes, long considered extremely loyal, mate switching has also been shown.

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Chondrology is the branch of anatomy that deals with cartilage.

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Alfred G. Gilman and Martin Rodbell were awarded the Nobel Prize in Medicine for the discovery of cell signalers called G-proteins.