General Science Questions (MCQs) for Competitive Examinations

Notes:
Fertilization in plants is not directly influenced by sunlight. Fertilization occurs after pollination, when pollen grains land on the stigma of a flower of the same species. During this time, a series of events take place leading to the formation of seeds. However, none of these event is affected by presence or absence of light.

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Root hairs are tubular-shaped tip-growing cells that arise from epidermal cells known as trichoblasts, behind the tips of young roots. Like all tip-growing cells, root hairs grow by the addition of cell wall precursors to the tip delivered by vesicles from the endomembrane system.

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Cell wall is found in plants, bacteria, fungi, algae, and some archaea. Animal cells do not have cell walls, nor do protozoa. It is a structural layer situated outside the cell membrane that provides the cell with both structural support and protection, and also acts as a filtering mechanism.

Notes:
Buccal cavity (oral cavity) refers to the mouth cavity: the beginning of the alimentary canal, which leads to the pharynx and (in vertebrates) to the oesophagus. It is part of the digestive system. In mammals it contains the tongue and teeth, which assist in the mechanical breakdown of food, and the openings of the salivary glands.

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Metamorphosis is a process by which animals undergo extreme, rapid physical changes some time after birth. Commonly known examples of metamorphosis include the process undergone by most insects, and the transformation of tadpoles into frogs. Hormones called molting and juvenile hormones, which are not species specific, apparently regulate the changes.

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Water catchment areas such as forests are continually being destroyed through deforestation to pave way for human settlement. This problem has been brought about by rapid population increase. As a result, there is not enough rain thus causing water shortage.

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The Cell theory, first developed in 1839 by Matthias Jakob Schleiden and Theodor Schwann, states that all organisms are composed of one or more cells, that cells are the fundamental unit of structure and function in all living organisms, and that all cells come from pre-existing cells. Cells are called the ‘Building Blocks of Life’ or the ‘Basic units of Life’.

Notes:
Breathing is the process in which air moves in and out of the lungs with the help of various respiratory organs. The process of taking in air rich in oxygen is called inhalation. Similarly, the process of giving out air rich in carbon dioxide is called exhalation. When we inhale, the ribs move up and outwards while the diaphragm moves down. An exact opposite movement occurs during exhalation when the ribs move down and inwards while the diaphragm moves up.

Notes:
Dark fermentation is the fermentative conversion of organic substrate to bio-hydrogen. It is a complex process manifested by diverse groups of bacteria, involving a series of biochemical reactions using three steps similar to anaerobic conversion. Wastewater is used as a potential substrate for bio-hydrogen production in the dark fermentation process.

Notes:
Test tube baby is born from in vitro fertilization. In vitro fertilization (IVF) is a process by which an egg is fertilized by sperm outside the body: in vitro. When a woman’s natural cycle is monitored to collect a naturally selected ovum (egg) for fertilization, it is known as natural cycle IVF. The fertilized egg (zygote) is then transferred to the patient’s uterus with the intention of establishing a successful pregnancy.