FH2921-BIOLOGY-Harvard | EssayIvy.com

Exam 1

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1. Ionizing radiation causes temporary or permanent mutational changes to the genetic

material of cells by altering DNA coding. Ionizing radiation causes electrons and molecules in

the human body to lose or gain electrons and cause impacts such as the breakdown of essential

chemical bonds in the body, production of harmful free radicals, creation of new harmful

chemical bonds and damage to the DNA cell structure. An example of the ionizing radiation

source is nuclear medicine therapy which uses radioactive isotopes in diagnosis and treatment of

cancer.

2. The aquatic ecosystem is an entity formed by interaction between living organisms and

physical environment found in water. It comprises biotic and abiotic. The plants in the lake

ecosystem are the producers, small fish, and aquatic animals that only feed on plants are the

primary consumers, secondary consumers are the marine animals that are omnivorous and feed

on the primary consumers besides plants. These animals include big fish, crocodiles and

hippopotamus among others. Tertiary consumers are the bacteria and animals that obtain their

nutrients from the dead organisms including producers, primary and secondary consumers. The

abiotic factors affecting the lake include the non-living environmental chemical and physical

factors that determine how living organisms interact and survive such as water clarity, depth,

salinity, temperature, acidity, light availability, stratification, currents, tides, nutrients, water flow

rates and dissolved oxygen (Bardgett et al 2010).

3. Both animals and plants also act as a source of carbon when they die and decompose. Plant

forests are the sink for carbon since they use carbon dioxide for photosynthesis and store it in a

different form. These sources and sink ensure interdependence among living organisms.

However, some factors such as natural and man initiated calamities that result in the massive

Exam 3

death of organisms may cause imbalance. The imbalance negatively impacts the remaining

organisms for instance too much carbon accumulation due to plant death may lead to suffocation

of animals Source of nitrogen is production and use of fertilizers while dead plants in a large

forest are sinks for nitrogen since they decompose slowly over an extended period of time to

release nitrogen. These sources are important since they ensure adequate and not the excess

release of nitrogen to the environment. Imbalance can ensue in instances of destruction of ozone

layer leading to nitric oxide and oxygen chemical reaction. This may bring about the effect of

global warming just like other greenhouse gasses.The source of phosphorus is rocks and soil

while its sink is ocean sediments. Phosphorus is essential in building the genetic materials of

both animals and plants. Imbalance of phosphorus in the environment such as being excess can

lead to a blooming of plant growth cover in the water services and prevent oxygen from

dissolving freely in water, essential for aquatic life.

4. According to the 2015 demographic estimate, comparative data about Botswana is as follows:

Botswana

life expectancy

54.18 years

79.68 years

fertility rate

2.33 children born/woman

1.87 children born/woman

birth rate

20.96 births/1,000

12.49 births/1,000

death rate

13.39 deaths/1,000

8.15 deaths/1,000

Botswana histogram indicates a high population of the young population and sharp decline with

an increase in age. Annual income is expected to be higher in Botswana since it is majorly

composed of a young age population reproductive as opposed to the US. Education for women

Exam 4

and equal rights is more likely to be experienced in the US as opposed to Botswana due to

cultural issues and population representation (The CIA World Fact book, 2014).

5. Exposure of the human body to lead can result in the destruction of the nervous system

mental diseases in fetuses and young children. It causes multi-organ system failure in adults.

Sources of lead are leaded petroleum products, paints, smelting and cosmetic products. Exposure

to lead can be prevented by policies that abolish the use of it in cosmetics, gasoline, and paints.

6. Poor quality of air results in respiratory diseases. Pollution occurs by using aerosol chemicals,

industrial emission of smoke. Diseases that are caused are asthma, pneumonia, chronic

obstructive pulmonary disease and throat cancer. People affected are the aged, infants and the

people already suffering from other heart and respiratory diseases (Bardgett et al, 2010).

7. Mercury gets into the environment from volcanic eruptions, exhausts fumes of the power

station. Once in the atmosphere, it combines with rain water and transformed by microorganisms

methyl mercury that is absorbed by planktons, the food for fish. It gets to humans by

consumption of affected fish. It affects the nervous system and causes tremors, cognitive and

motor dysfunctions mostly in the young children and babies. Mercury pollution can be controlled

by installing equipment that collects vapor from exhaust fumes or using a retort to collect it as it

is boiled off during its separation from gold. (Hoefnagels, 2013)

8. Human energy is the ability of a person to perform a certain task. Humans obtain it in the form

of adenosine triphosphate produced during metabolism of ingested food. It is used for muscle

movement. Plants are the primary source of human energy, Carbohydrates, proteins, minerals,

vitamins and fats being the essential components of body energy. Energy is used in performing

activities, thinking and in tissue repair after injury. Absence of the plants in nature can lead to

Exam 5

deficit of the above components, and this leads to impaired body mechanisms, reduced body

resistance to infections and delayed wound healing

9. Energy conservation can be done through lowering room temperature by use of a thermostat,

reducing power consumption that maintains room temperature. ($ 20), fixing air leaks through

proper insulation to prevent heat loss ($30), using natural light and switching off the lights

during the day ($0), doing home energy audit to know the areas in the home losing a lot of

energy and intervene early ($40), using energy efficient appliances that have energy star rating

($0). However, it’s hard to use a less than $100 initial cost in energy conservation.

10. Most of the non-hazardous wastes in the US are disposed of in landfills and

incineration. Biological wastes are often managed through decomposition in landfills and

recycling. However, management by incineration and landfills poses a health risk through

air pollution and sipping of the decomposed material through the ground to contaminate

water sources. Hazardous wastes are managed by standardized systems through treatment

before being released into the environment (Bardgett et al 2010).

Exam 6

Bibliography

Bardgett, Richard D, and David A. Wardle.2010. Aboveground-belowground Linkages:

Biotic Interactions, Ecosystem Processes, and Global Change. Oxford: Oxford University Press.

Hoefnagels, Marille. 2013. Biology: The Essentials. New York: McGraw-Hill.

The Cia World Factbook .2014. New York, NY: Skyhorse Publishing.

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