Match the topic sentences to their correct paragraphs about limiting factors

a) Temperature can act as a limiting factor.

b) During the winter, some mammals become dormant, or hibernate.

c) Temperature may have a significant effect on the appearance of organisms.

d) Animals that maintain themselves at their optimum temperature are warm-blooded or homoeothermic.

1. __________ At this time, the body temperature (normally about 100°F) falls to 45°F or even lower. The heart beat of a ground squirrel drops from a summer average of over 200 beats per minute to an average of less than 20 beats per minute in the winter.

2. __________ For example, the distribution of the polar bear is limited to regions in which the temperature averages no higher than 32°F. On the other hand, the malarial parasite does not develop when the temperature goes below 77°F.

3. __________ In other words, the weather outside can change, but they will keep the same temperature. If this temperature regulator doesn't work, however, the animal will die. If a person is kept in cold weather for too long, the temperature of his/her body will fall. When a person's body temperature falls to 65°F, the heart will fail.

4. ____________ The Himalayan rabbit is mostly white but has black ears, tail, and feet. If the hair is taken from a white area, it will grow back white if the animal is kept at room temperature (68°F). However, if the animal is kept at a temperature below 50°F, the hair will grow black.

XIV. Now see if you can write your own topic sentences for these paragraphs about ecosystems.

1. ____________ For example, they both have long, cold winters. In addition, neither of these ecosystems has trees. The tundra has mostly low-lying plants, while the grassland has grasses.

2. ___________ The biotic component consists of all the living things in the ecosystem. The abiotic component consists of energy, matter, and physical factors. Physical factors include things like precipitation, wind, and soil. All of these elements help determine what occurs in a particular ecosystem.

XV. Here is a list of some physical factors that determine what plants and animals can live in certain ecosystems. Can you rearrange the letters to solve the puzzle?

1. aeeemprrttu, 2. ilos, 3. iwdn, 4. npatpeoriiict, 5. ghilt, 6. aceilmt, 7. itseturnn, 8. ymutihdi

Physical Factors

XVI. Look at the following pictures. Can the koala bear in the left picture live in the same place as the polar bear? Why or why not? What physical factors are different in each of their ecosystems?

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