Biology MCQs

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Cyanobacteria, also known as blue green algae, are single-celled and belong to the family of Prokaryotes. That means, they do not have a well defined cell nucleus. The ability of cyanobacteria to perform oxygenic photosynthesis is thought to have converted the early reducing atmosphere into an oxidizing one, which dramatically changed the composition of life forms on Earth by stimulating biodiversity and leading to the near-extinction of oxygen-intolerant organisms.

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Monotremes are mammals that lay eggs instead of giving birth to live young like marsupials and placental mammals. Among living mammals they include the platypus and four species of echidnas (or spiny anteaters).

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Cabbages have no need to store food as they are seasonal plants and die after about 4 to 6 months. They do however produce food in the leaves of the plants and would utilize short-term storage (in the leaves) for simple metabolic processes.

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Plasma is a straw coloured, viscous fluid constituting nearly 55 per cent of the blood. 90-92 per cent of plasma is water and proteins contribute 6-8 per cent of it. Fibrinogen, globulins and albumins are the major proteins. Fibrinogens are needed for clotting or coagulation of blood; while, globulins primarily are involved in defense.

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Oxygen is one of several dissolved gases important to aquatic systems. Dissolved oxygen is necessary to maintain aerobic conditions in surface waters and is considered a primary indicator when assessing the suitability of surface waters to support aquatic life. Dissolved oxygen can be measured in two ways: either in milligrams per litre (mg/L) or percent saturation (% sat). Water with an oxygen concentration of less than 3 mg/L will generally not support fish. When concentrations fall to about 3-4 mg/L, fish start gasping for air at the surface or huddle around the water fall (higher concentration points). Above 5 mg/L, almost all aquatic organisms can survive indefinitely, provided other environmental parameters are present within allowable limits.

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Red blood cells, also called erythrocytes, are the most abundant cell type in the blood. The primary function of red blood cells is to transport oxygen to body cells and deliver carbon dioxide to the lungs. Red blood cells are derived from stem cells in red bone marrow. These cells have a life-span of about 120 days.

Notes:
• Budding reproduction occur in Hydra. Budding is an asexual mode of producing new organisms. Both hydra and yeast reproduce by the process of Budding.
• Fragmentation: Cyanobacteria, fungi, flatworms, sponges, some annelid worms and sea stars.
• Binary Fission: Amoeba, E. coli, Archaea, euglena etc.
• Spore formation: Fungi, bacteria, Algae etc.

Notes:
DNA stands for Deoxyribonucleic acid. It is a nucleic acid that carries the genetic instructions used in the growth, development, functioning and reproduction of all known living organisms and many viruses. DNA and another nucleic acid RNA are one of the four major types of macromolecules that are essential for all known forms of life along with proteins, lipids and complex carbohydrates (polysaccharides).

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Mycology is the branch of biology concerned with the study of fungi, including their genetic and biochemical properties, their taxonomy and their use to humans as a source for tinder, medicine, food, and entheogens, as well as their dangers, such as poisoning or infection. From mycology arose the field of phytopathology, the study of plant diseases.

Notes:
Vitamin B contains nitrogen atoms that allow them to participate in regulating metabolism. For example, Vitamin B3 is a water soluble vitamin containing compound Niacin or Niacinamide, a nitrogen containing vitamin.