Biology MCQs

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Arthropoda is the largest phylum of animal kingdom because around 2/3rd of all the named species on Earth belong to this phylum.
Ants, mosquitoes, flies, cockroaches, shrimp, crabs, spiders, scorpions etc. are examples of arthropods. There are three main classes of arthropods as follows:

• Insects: This includes mosquitoes, cockroaches, ants, flies, bees, moths, grasshoppers, beetles and butterflies
• Crustaceans: This includes crabs, lobsters, shrimp and barnacles
• Arachnids: This includes scorpions, spiders and mites

Further, a few other classes are onychophorans (velvet worms), diplopods (millipedes) and chilopods (centipedes).

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The spleen, which is located under the ribcage and above the stomach in the left upper quadrant of the abdomen is the largest organ in the lymphatic system. It is that organ where RBC are selectively destroyed/ recycled by macrophages.

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Rennin which is also known as Chymosin, is a proteolytic enzyme related to pepsin that is synthesized by chief cells in the stomach of some animals. Its role in digestion is to curdle or coagulate milk in the stomach.

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Earthworm contributes to the replenishment of soil. As the earthworm moves through the soil, it creates burrows. This allows air and water to move more readily through the soil. The worms also feed on the decaying organic matter, which helps to improve soil fertility.

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Please note that Polar Bear is the largest land carnivore animal, weighing about 350 to 700 kgs.
Kodiak bear which is also of same size is a Omnivore

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Necrosis is the name of premature death of cells and living tissue. It refers to the death of most or all of the cells in an organ or tissue due to disease, injury, or failure of the blood supply.

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Apomixis is reproduction where only one parent passes genes to the offspring. Apomictically produced offspring are genetically identical to the parent (clones). The method is most seen in plants, especially flowering plants. Brambles (blackberry) are apomictic. Some authorities give “reproduction by special tissues without fertilisation”, or “asexual formation of a seed from the maternal tissues of the ovule, avoiding meiosis and fertilization, leading to embryo development”. (Wikipedia Simple)

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The phenomenon that causes animals to sweat to reduce temperature and change electrolyte concentration is homeostasis. When core body temperature increases, sweat glands respond by cooling the skin. Blood vessels also dilate, which allows the body to release more heat. Sweating is a rare ability in the animal kingdom. For example, rats don’t sweat when their core body temperature rises to 41°C. However, they do sweat in response to pilocarpine and other cholinergic agonists.

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The internal walls of the small intestine are covered in finger-like tissue called villi. Each of these villi is covered in even smaller finger-like structures called microvilli. These villi and microvilli increase the surface area available for the absorption of nutrients.

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Rickets is a skeletal disorder that’s caused by a lack of vitamin D, calcium, or phosphate. These nutrients are important for the development of strong, healthy bones. People with rickets may have weak and soft bones, stunted growth, and, in severe cases, skeletal deformities.