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Biology-2 QWC Practice Questions & Answers

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´╗┐Biology-2 QWC Practice Questions & Answers 1. Compare the internal structures of bacterial and yeast cells with those of plants and animals Bacterial, fungal (yeast), animal and plant cells all have various common features; all have a cell membrane, cytoplasm and a form of genetic material. However, in a bacterial cell, this genetic material is presented in an alternative form; unlike the other cells which have their DNA contained inside the nucleus of the cell, a bacterial cell has their DNA found in a `loop` or strands of DNA in the cytoplasm. Another difference in a bacterial cell, is that they may contain a `whip-like tail` called Flagella so they have the ability to move around, a feature not necessary in the cells of plants, animals and yeast. A feature that an animal cell does not have, in comparison to the 3 other cell types, is a cell wall, this is because a cell wall ensures that the cell is strengthened and prevents the bursting of the cell, however an animal will not need this feature because they will grow, rather than expand. What particularly differentiates a Plant cell to the other cells, are that they contain chloroplasts inside them, which enable them to absorb light and subsequently photosynthesize; their form of making food. To make food for an animal cell, animals simply eat, food for fungal or yeast cells, are stored in a `food storage granule` and a bacteria?s source of food is created through protein synthesis within their ribosomes. All the cells apart from a yeast cell contain ribosomes, and only an animal and plant cell contain mitochondria. 1. Describe, with examples, the process of specialisation in cells. In animals, cell specialisation occurs at the beginning of their life; embryonic stem cells or `unspecialised cells` differentiate into the cells that make the animals body. However, animals cannot maintain cell differentiation throughout their lives; once a cell is specialised, they cannot become a stem cell once again; the genes for their particular ...read more.


To meet this demand, the heart begins to pump blood at a quicker pace compared to the resting rate, and in doing so can supply the muscles with the oxygen they require to respire. This is respiration and occurs normally, even when sitting still, but occurs at a higher rate when running slowly. The equation for respiration is: Oxygen + Glucose Water + Energy + Carbon Dioxide. However, if the athlete begins to speed up, or has been running for a long duration, it is likely they will anaerobically respire; this is when little amounts of oxygen and glucose create lactic acid and small doses of energy. Anaerobic Respiration cannot be kept up for a long amount of time; this is because the lactic acid is toxic and causes muscle fatigue, so the muscles cannot keep working. Also, the energy supplied in anaerobic respiration is too little to keep going on. 1. Describe the changes that take place in the human body during exercise to ensure that the muscles receive enough oxygen and what happens if the oxygen is in short supply. During exercise of the Human Body, the heart beats at a quicker pace to meet with the demands of respiration in muscle cells, so they are able to keep contracting and ensuring movement. This requires Glucose and Oxygen, and Water, Energy and Carbon Dioxide are released as a result. However, when the oxygen is in short supply, your body still needs to continue respiring, and so anaerobically respires. Anaerobic respiration consists of little amounts of oxygen combined with glucose to release lactic acid and small doses of energy. The lactic acid, however, is toxic and causes muscle fatigue and pain. The small doses of energy are not enough for the human body to continue exercising at a high rate, and your body must pay back and Oxygen Debt. An Oxygen Debt consists of repaying back the oxygen that did not enter the body during anaerobic respiration, it also neutralises and oxidises the build-up of lactic acid and removes it from the body so it can no longer cause pain. ...read more.


Another way for an organism to become fossilised is when one or more conditions for decay are absent, or that when the organism is decaying, parts of it are replaced by other materials so we still have an outline or idea of the original organism. The traces of an organism can also be preserved, for example, footprints or burrows. It is also possible that whole animals, even with their soft tissue, can be preserved; this is done as they can become fossilised in amber or ice, which rapidly preserves them and does not allow conditions for decay to occur. 1. Outline the possible causes of extinction Extinction is when all organisms of a species have died out and there is no possibility of future generations. There are many factors which can be the source of extinction, sometimes there are a whole variety of factors which contribute to the extinction of a species. One possible cause of extinction could be the arrival of a new competitor, whom has a more successful adaptation to enable them to capture more prey and subsequently wipe out the original species? food source. Without a food source, the organisms will not be able to survive which could lead to their eventual extinction. Another cause could be the arrival of a new predator, which could eliminate all members of a species, when combined with all predators. The Dodo Bird encountered both the arrival of new competitors and predators, when humans inhabited their islands and bought along with them threatening pets. Another possible cause of extinction would be if a disease was introduced to a species, and cause extinction before the organisms develop immunity against it. Finally, another possible cause of extinction could arise from one single catastrophic event, a famous example being the extinction of the dinosaurs in which it is thought that a large meteorite struck the Earth and eliminated almost all life. Other single catastrophic events could include Super Volcanic Eruptions or Deforestation. ...read more.

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