Questions+and+Answers+from+Unit+7+The+Dynamics+of+Ecosystems

Ecological pyramids are a way of representing the different trophic levels in an ecosystem using rectangles. Each rectangle represents a trophic level. Food webs are made up of many food chains linked together. It is a pyramidal structure that shows the number of organisms
 * __ UNIT 7 THE DYNAMICS OF ECOSYSTEMS (LAST PART)PAGE 38, 39,40, 41, 30): __**
 * 1.- What are ecological pyramids?**
 * 2.-What are food webs made up of?**
 * 3.- What is a pyramid of numbers?**

4.- **Where do we find the producers and the top carnivores in an ecological pyramid?** Producers are at the base of the pyramid and the top carnivores are at the top of the pyramid. Decomposers are not found in them because they feed on the organic remains of all living things, so they cannot be located in a single trophic level. Because the size of each rectangle is proportional to the values it represents (energy, biomass or number of individuals). 7.-**What are the names of the three different types of pyramids?** Energy pyramids, biomass pyramids and pyramids of numbers. Energy pyramids measure g/m2/year; biomass pyramids measure g/m2 and pyramids of numbers measure the number of individuals. Label the pyramids on the board. This occurs when a few large individuals are food for many smaller individuals or when the producers’ reproduction rate is very high.
 * 5.- Why are decomposers not represented?**
 * 6.- Why do the rectangles in an ecological pyramid have to be a particular size?**
 * 8.-What do each of the pyramids measure?**
 * 9.- When can ecological pyramids be inverted?**

10.- Write some differences between K-strategists and R-strategists.

a) R-strategists are very well adapted to the environment. False, K-strategists are very well adapted to the environment. b) K-strategists maintain a stable population with a controlled growth. True c) K-strategists spend part of the year in a lethargic state. False, R- strategists spend part of the year in a lethargic state. d) Lynxes and oaks are K-strategists. True virgin areas are quite inhospitable places. You could provide them with visual examples of sand dunes, lava deposits or bare rock, or ask them to imagine what life would be like there. Secondary succession takes place in ecosystems that have suffered a regression. Secondary succession occurs much faster. Biodiversity, the number of trophic levels, the amount of biomass and the stability of the ecosystem all increase. Oxygen and hydrogen are the two most important elements. Carbon, nitrogen, phosphorus and sulphur Biogeochemical cycles are the movements of chemical elements in nature, in which both organic and inorganic matter are involved. Carbon returns to the atmosphere as CO2 through the respiration of all living things. Animals use carbon in the form of organic matter, which is then transferred from one animal to another. They use CO2 stored in the atmosphere to synthesise organic molecules through photosynthesis. a) Lithosphere Limestone, coal and oil b) Biosphere Organic compounds c) Atmosphere Carbon dioxide If we apply the ten percent rule, we can deduce that producers will have 100, primary consumers will have 10, secondary consumers will have 1 and tertiary consumers will have 0.1 units of energy.
 * 11.-Read the following statements and say if they are true or false. Correct the false statements.**
 * 12.- Why do you think there are no communities established in virgin areas?**
 * 13.- In which ecosystems can secondary succession take place?**
 * 14.- Which succession occurs faster, primary succession or secondary succession?**
 * 15.-Which factors increase in a succession?**
 * 16.- What are the most important chemical elements?**
 * 17.- What are the other important elements?**
 * 18.- What are biogeochemical cycles?**
 * 19.- How does carbon return to the atmosphere?**
 * 20.- How do animals use carbon?**
 * 21.- How do autotrophic organisms use carbon?**
 * 22.- Identify in which form carbon is found in the following layers of the Earth:**
 * 23.- If 1000 units of energy enter an ecosystem, how many units of energy will be available for tertiary consumers?**