Living organism in the ecosystem

1. Food chain and food webs:

1. Which of the organisms in this food web gets energy from both producers and consumers?
   1. Shrimp
      1. The shrimp gets energy from both the snail and algae.

1. What organism is a primary consumer in the food web?
   1. Grasshopper
      1. Primary consumers are organisms that eat the producers. The grasshopper is considered a primary consumer because it eats the grasses, which are producers.
      2. The hawk and coyote are secondary consumer.

1. A food chain is represented below.
   1. Phytoplankton ⟶ Krill ⟶ Mackerel ⟶ Sea gull. Which organism in the food chain is a primary consumer?
      1. Krill – The krill eats the phytoplankton, so it is a primary consumer.
2. Which organism in the food chain is a secondary consumer?
   1. Mackerel.
      1. The mackerel is a secondary consumer because it feeds on the krill, which is a primary consumer.
3. Which organism in the food chain is a producer?
   1. Phytoplankton
      1. The phytoplankton is a producer, beginning the energy flow of the food chain.
4. Which organism in the food chain is a secondary consumer?
   1. Mackerel
      1. The mackerel is a secondary consumer because it feeds on the krill, which is a primary consumer.
5. Which of the following is most likely to cause the greatest decrease in the snake population?
   1. A decrease in the mice population
      1. Mice are the food source of snakes. If the mice population was drastically reduced, there would be a decrease in the snake’s food supply, resulting in the decrease of the snake population.

2. Energy pyramids:

1. In what level of the energy pyramid are mice most likely found?
   1. C
      1. Mice are herbivores, meaning they consume the plants found in level D.

Animal	Diet
Mice	Grasses, clover
Hawk	Rabbits, snakes
Snake	Grasshoppers, mice

1. In what level of the energy pyramid are hawks most likely found?
   1. A
      1. Hawks are at the top of the food chain, eating the other organisms below it.

Animal	Diet
Mice	Grasses, clover, oats
Hawk	Rabbits, snakes, mice
Snake	Grasshoppers, mice, rabbits
Rabbits	Grasses, clover, oats

Pyramid of bio-mass vs pyramid of numbers:

3. Nutrient cycles:

1. What do biogeochemical cycles represent?
   1. How certain nutrients move through the environment and are continually used and recycled
      1. Biogeochemical cycles show how important nutrients move through an environment, and are recycled between living and nonliving forms.
2. Which of the following is true of biogeochemical cycles?
   1. They can be affected by human activity.
      1. Human activity can have a great effect on biogeochemical cycles.

3.1 The water cycle:

1. Which term best represents process 1?
   1. Evaporation
      1. During process 1, heat from the sun helps vaporize liquid water on Earth. This process of liquid water changing into water vapor is known as evaporation.
2. The diagram below depicts the water cycle, with key processes numbered. Which term best represents process 2?
   1. Transpiration
      1. During process 2, water enters through a plant’s roots, travels through its vascular system, and is released through its leaves as vapor.. This is known as transpiration.
   2. Condensation is represented by process 3, during which water vapor cools and turns into liquid droplets.
3. Which term best represents process 4?
   1. Precipitation
      1. During process 4, water droplets fall to Earth as rain, hail, or snow. This process is known as precipitation.

3.2 The Nitrogen cycle:

1. Which of the following steps of the nitrogen cycle is pictured?
   1. Denitrification
      1. Denitrification is the process where nitrogen gas is released back into the atmosphere.

1. Which of the following is an example of how biogeochemical cycles are important to sustaining life?
   1. Nitrogen waste from an organism is converted into usable nutrients for others.
      1. Elements found in waste produced by some organisms are later recycled via the appropriate biogeochemical cycle.

1. In which stage of the nitrogen cycle is atmospheric nitrogen converted into biologically usable forms?
   1. Nitrogen fixation
      1. Nitrogen is made bioavailable through the process of nitrogen fixation. During this process, bacteria and other single-celled prokaryotes convert atmospheric nitrogen into usable forms such as ammonia, nitrates, or nitrites.
2. Which part of the nitrogen cycle is pictured by the arrow?
   1. Ammonification
      1. Ammonification occurs when ammonium (NH4+​) is produced through decomposition.

3.3 The carbon-cycle:

1. Which of the following does NOT add carbon to the atmosphere?
   1. Photosynthesis
      1. Photosynthesis converts carbon dioxide into usable energy sources for plants. It does not return carbon to the atmosphere.

1. The diagram below illustrates part of the carbon cycle.

1. Carbon dioxide
   1. The cow takes in organic carbon as glucose and returns it to the environment as carbon dioxide gas, which is then taken in by plants during photosynthesis.
2. Which of the following is NOT a process that drives the carbon cycle?
   1. Ammonification
      1. Ammonification is part of the nitrogen cycle, not the carbon cycle

1. Photosynthesis converts carbon dioxide into usable energy sources for plants. It does not return carbon to the atmosphere.
   1. In cellular respiration, carbon is returned to the environment as carbon dioxide gas.
   2. Decomposers break down decaying organic matter, releasing carbon into the atmosphere.

4. Population Ecology:

4.1 Population attributes:

1. There are 50 frogs in a pond. Over the period of a month, 5 more frogs hatch and develop into adults. What is the per capita birth rate of this frog population?
   1. 0.1 births per frog per month
2. Rangers are trying to determine how many tigers are present in an area. Which of the following are ways in which the rangers might calculate tiger population density (N) in that area?
   1. Tracking of tiger droppings.
      1. DNA analysis of tiger droppings can identify individuals in the population, which helps calculate N
   2. Identification of tiger paw prints.
      1. Each tiger is thought to have distinctive paw prints, or pug marks. This is an indirect way to identify and count tigers, in order to determine N
   3. Counting the number of tigers spotted.
      1. Literally determining the number of animals in a region using cameras or human reports is one way to determine N.
3. The image below represents the age distribution pyramid of the population of Bermuda in the year 2010. Based on this information, which of the following statements about the population of Bermuda is true?

1. The population of Bermuda is declining.
   1. A declining population has more people in the reproductive age group than in the others. If the pre-reproductive group is smaller than the others, there will be less reproduction in the future, leading to a decline in population.
   2. Based on the given data, the population of Bermuda is declining.

1. The image below represents the age distribution pyramid of the population of the Philippines in the year 2015

1. Based on this information, which of the following statements about the population of Philippines is true?
   1. The Philippines has a declining population.
      1. A declining population has more people in the reproductive age group than in the others.
      2. From the 2015 age distribution, we can see that both pre- and post-reproductive groups are smaller than the reproductive. Therefore, the Philippines has a declining population.

1. Which of the following are ways in which the rangers might calculate elephant population density (N) in that area?
   1. Tracking of elephant droppings.
      1. DNA analysis of elephant droppings can identify individuals in the population, which helps calculate N.
   2. Counting the number of elephants spotted.
      1. Literally determining the number of animals in a region using cameras or human reports is one way to determine N
2. The image below represents the age distribution pyramid of the population of India in the year. Based on this information, which of the following statements about the population of India is true?

1. India has a growing population.
   1. A growing population has the maximum number of people in the pre-reproductive age group, fewer in the reproductive group, and least in the post-reproductive group. This ensures future growth of the population.

1. There are 96 coconut trees in a plot. Over the period of a century, 6 coconut trees die. What is the per capita death rate of the coconut tree population?
   1. 0.0625 individuals per coconut tree per century
2. There are 200  deer in a field. Over the period of a year, 40 more deer are born. What is the per capita birth rate of this deer population?
   1. 0.2 births per deer per year

4.2 Population growth and decline:

1. A single bacterium is transferred to a pond. It begins to divide, giving rise to 2 new bacteria with each division. The image below depicts the growth of the bacterial population in the pond over 12 hours, Based on this growth curve, which of the following statements about the bacterial population are most likely to be true?

1. The bacteria have unlimited food resources in the pond.
   1. From the image, we can see that the bacteria are growing exponentially. This can only happen if they are not limited by availability of food resources.
2. A new species of moth gets introduced to an area, and begins to proliferate. Some moth specialists study the pattern of moth population growth and plot it in the image seen below. Based on this data, which of the following are conclusions that the specialists are most likely to make about this plant?

1. The region has reached its carrying capacity for the moth population.
   1. From the image, we can see that the moth population has reached an upper limit, and is no longer increasing in number. This indicates that the region has reached its carrying capacity for the moth population.
2. The moth population might be prey to certain predators.
   1. From the image, we can see that the moth population has reached an upper limit, and is no longer increasing in number. Predators that keep the moth population in control by eating them might be one explanation for this logistic growth pattern.
3. There are 350 fish in a pond. Over the period of a month, 125 more fish hatch, 35 immigrate to the area, and 75 swim away to a different region. Also, 40 fish die during the same period. Which of the following statements correctly describes the change in fish population density over the month?
   1. There is an increase in fish population density.
4. There are 75 lions in an area. Over a period of 2 months, another 13 lions are born, and 9 new lions immigrate to the area. The new lions battle and kill 17 lions from the population, and 23 others leave the area permanently. Which of the following statements correctly describes the change in lion population density over that time period?
   1. There is a decrease in deer population density.
5. There are 500 flamingos in an area. Over the next year, another 50 flamingos are born, 20 immigrate to the area, and 30 fly away to a different region. Also, 15 elderly birds die during the same period. Which of the following statements correctly describes the change in flamingo population density over the year?
   1. There is an increase in flamingo population density.