Enviromental Science Midterm Short Answers

Question 1

Some scientists conducted an experiment in which they evaluated various measurements of human health in people who drank at least one cup of coffee a day. They found no significant differences in these health indicators in the subjects who drank only one cup of coffee a day and those who drank as many as 20 cups a day. They concluded that coffee has no adverse effects on human health. Write your answers to the following in the spaces below.
a. What were the independent and dependent variables in this experiment?
b. Do you agree with the conclusion the scientists drew from their results? Why or why not?

Answer 1

a- independent variable: How many cups of coffee the person drank.
dependent variable: Human health after drinking the cups of coffee.

b- I do not agree, because there is not enough information since there is no control group.

Question 2

Explain how environmental problems can be local, regional, or global. Give one example of each.

Answer 2

It could be local if you catch and eat a certain type of fish in a pond that has been eating and invasive species. It could be regional if a forest caught on fire and many animals lost their homes. It could be global if the weather continued to get hotter and ocean levels continued to rise.

Question 3

List 2 environmental problem(s) for each that can be caused by the following:
a. Acid rain
b. Destruction of the rainforest
c. Poaching
d. Overfishing
e. Mining
f. Extinction of blue whales
g. Smog
h. Pesticide use
i. Burning of coal

Answer 3

A- Unclean soil & unclean drinking water.
B- Less food sources, and population decline.
C - Population decline and no food source.
D- Population decline and a species could now have no predators.
E- Contamination on the ecosystems around it and unhealthy soil.
F - Rise in population in krill and a loss of a food source for orcas.
G- Bad air quality and unhealthy environments.
H- Poisoning food and population decline.
I- Bad air quality and toxins releasing.

Question 4

What is the major difference between the effect of a predator on its prey and the effect of parasites on their hosts?

Answer 4

When a predator eats its prey, the prey is usually dead and not living. On the other hand, when a parasite is on the host, the host is still living, and the parasite needs the host to live in order to stay alive

Question 5

In the tropics, two species of mites (small arthropods, relatives of spiders) live in flowers that hummingbirds visit. The hummingbirds feed on flower nectar and spread pollen from flower to flower. The mites feed on the nectar. They travel from flower to flower by riding on the beak of the hummingbirds. No flower contains both species of mites, and experiments have shown that male mites of different species act aggressively toward each other. In the space provided, give the name of the interaction that fits best.

(a) Hummingbird and flower
(b) The two mite species
(c) Flower and mites

Answer 5

a- Mutualism
b- Parasitism
c- Commensalism

Question 6

Species interact in a variety of ways. Several kinds of interactions have are discussed. The following are statements of these interactions. In the space provided, give the name of the interaction that best fits the following:
(a) A resident bacteria that helps a mammal’s digestion and in turn receives nutrients. Interaction between the mammal and the bacteria:
(b) A lion kills and eats a zebra. Interaction between lion and zebra:
(c) When you take an antibiotic for a bacterial infection, it kills those bacteria. Interaction between bacteria and you before the antibiotic:
(d) Two students both steal reserve readings from the library in order to get the highest grades on the curve. Interaction between the two students:

Answer 6

a- mutualism
b-Predation
c-Parasitism
d- competition

Question 7

Your roommate has a small enclosure for with plants, algae, snails, and a lizard. Which of the following terms best describes the enclosure: community, population, environment, ecosystem, and a habitat? Explain your reasoning

Answer 7

An ecosystem would best describe the enclosure. This is because an ecosystem how all the organisms within a certain area interact with each other. In the enclosure, all the organisms are working together which makes an ecosystem.

Question 8

Give three examples of nonliving (abiotic) components of an ecosystem.

Answer 8

1- Temperature
2- Water
3- Soil

Question 9

Explain why vegetarians use food energy more efficiently than non-vegetarians.

Answer 9

Vegetarians use food energy more efficient because it takes less energy to produce plant-based products. To get the meat-based products, it takes more energy.

Question 10

When feces and dead grass are left on the ground, they “disappear.” Why?

Answer 10

Feces and dead grass eventually break down after being left on the ground. Once they break down, they make the soil they enter more fertile and richer. They decompose into the ground.

Question 11

Fundamental characteristics of energy are reflected in the first and second laws of thermodynamics (energy laws). Define these two laws.

Answer 11

First Law- Energy cannot be created or destroyed. Energy just changed from form to form.
Second Law- States that heat always flow from hotter to colder regions. It tells us how energy changes form.

Question 12

You set up a closed system – an aquarium with only snails and bacteria. The snails eat bacteria and the bacteria feed on snails. Explain why this system can’t persist.

Answer 12

This system cannot persist because eventually one of the organisms will die of because they both feed on each other. Once one organism dies, the other will not have anything to eat, resulting in it dying.

Question 13

A mouse and a cricket in an ecosystem both feed on rye grass. The mouse also eats crickets and coyotes eat mice and crickets. What are the respective trophic levels of all of these organisms? Diagram a food web.

Answer 13

Prodcuer: Rye Grass
Primary Consumer: Cricket
Secondary Consumer: Mouse
Tertiary Consumer: Coyotes

Question 14

An ecosystem must lie between a source of usable energy and a sink for degraded (heat) energy. What would happen to the system if there was energy input but no sink for degraded energy?

Answer 14

If there was no sink for degraded energy, then the heat would continue to rise. If there was a steady input of heat energy, but nowhere for it to escape, then the temperature would rise.

Question 15

Of the following processes, circle the ones associated with heterotrophs and underline the ones associated with autotrophs.
Primary production
Photosynthesis
Respiration
Secondary production

Answer 15

Heterotrophs: Secondary Production

Autotrophs: Primary Production, Photosynthesis, Respiration

Question 16

List and explain the human causes for the loss of biodiversity.

Answer 16

Some human causes of biodiversity include poaching, deforestation, and climate change. Poaching is when you kill animals for their body parts. Deforestation is cutting down forest and trees and making building something in that area or making something new. Climate change is making our world hotter and is causing many problems such as sea levels rising.

Question 17

Explain the ESA

Answer 17

The ESA is the Endangered Species Act. It is an act that protects endangered animals and plants and the locations they are found. This will hopefully lead to the population growing.

Question 18

Why do biologists favor using an ecosystem approach to preserve biodiversity?

Answer 18

Biologist favor this because it shows that they can sustain biodiversity by themselves. It shows that humans are a main reason that there is not a lot of biodiversity. It shows how the species will act on their own and out of control of humans.

Question 19

Describe three ways that preserving biodiversity can come into conflict with human interests.

Answer 19

1- Humans cannot hunt animals, just to sell their body parts. An example would be killing sharks for their fins or killing rhinos for their horns.
2- Humans cannot keep cutting down so many trees. If humans keep destroying forest, they are destroying homes of many animals.
3- Climate change is causing many animals to lose their homes or have other problems. Climate change makes the water levels rise because of the weather becoming hotter and hotter.

Question 20

Propose a way in which hunting or harvesting of plants or animals by humans can increase or protect biodiversity. Explain how it would help and what results could occur.

Answer 20

A way hunting or harvesting would increase biodiversity would be if you were hunting and invasive species. Invasive species are species that are not native to a certain area, and cause harm to the ecosystem. An example of this would be the Burmese python in Florida. It has no natural predators and eats everything in its way causing less biodiversity.

Question 21

Explain how the loss of a predator from a small island will affect not only the population of the prey species, but also of the other species in that ecosystem.

Answer 21

If a predator is no longer able to hunt the prey species, the population of that species is going to increase since there is nothing to eat it. The other species of that ecosystem are probably not going to do ass good. This is because whatever the original prey species was is going to be eating way more food since there will be more. This will ultimately lead to a population decrease in other species.

Question 22

When writing a Recovery plan, what are the categories for the species, and which one is most likely to get the most funds?

Answer 22

The categories for a recovery plan are vulnerable, endangered, and critically endangered. The one that is most likely to receive the most funds it critically endangered since the species that is critically endangered is closest to extinction.

Question 23

What is CITES and why was it established?

Answer 23

CITES is the Convention on International Trade in Endangered Species. It was established to make sure that international trade did the impact the survival chances of endangered species or plants.

Question 24

Explain captive breeding. Can it be successful? What species is it not successful?

Answer 24

Captive breeding is keeping plants or animals in controlled environments, to ensure the survival and population increase of a species. Yes, captive breeding can be successful in most cases, but it is usually not successful in the amphibian species.

Question 25

Population size may be limited by density-dependent or density-independent effects. Distinguish between these effects and give one example for each to support your answer.

Answer 25

Density independent is caused by abiotic factors, while density dependent is caused by biotic factors. Density independent does not matter about population. This means that if a hurricane came through it will affect that species whether it is small or large. A hurricane would be an example of independent and predation and competition would be an example of dependent.

Question 26

The demographic transition suggests a way of dealing with the problem of rapid population growth in poorer nations. This solution is humane and dignified. Briefly describe what it is and why it should work.

Answer 26

The solution would be instead of having so many babies that don’t live as long, have less babies that end up living longer. This would cause the population growth to become steady. This might also help to poor countries, because if these people are living longer their conditions of life are improving making the country less poor.

Question 27

You are observing a population of wolves as part of a research project. You note that wolf pups have a mortality rate of 40 percent in the first year. Adult wolves have a mortality rate of 25 percent. What type of survivorship pattern do the wolves display? Explain your answer

Answer 27

This would display a type III survivorship curve. This is because there is a high mortality rate when they are young, but once they are old, they have a high chance of survival.

Question 28

The types of biomes will be a matching section of your exam. List all the biomes and a characteristic of each.

Answer 28

a) Taiga - longer winters, short summers, poor soil
b) Tundra - cold are largely treeless
c) Chapparal - mixture of shrubs and open woodlands
d) Temperate Deciduous Forest - Include many trees and they lose their leaves.
e) Temperate Grasslands - primarily made up of grass and shrubs
f) Desert - little precipitation and no biodiversity. Lots of sand
g) Savana - Open grassland with few trees
h) Tropical Rainforest - many trees and vegetation and receives a lot of rain.

Question 29

Unlike the jungles you see in the movies, the floor of an undisturbed tropical rainforest usually lacks vegetation. Explain why.

Answer 29

The rainforest floor usually lacks vegetation because it gets no sunlight. The plants, leaves, and tree of the rainforest are so thick in dense they allow little if any sunlight to the floor. Plants need sunlight to grow, so without sunlight there will be no vegetation.

Question 30

Using the Planet Earth videos, choice four animals from at least two different biomes and explain what adaptations they have for that biome

Answer 30

Polar bears live in the tundra. Some adaptations they have is that their fur is white, so they blend in with the snow and they are great swimmers.
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