B1 Topic 3 - Inter-relationships

Question 0

What are the four main types of drugs and how do they affect an individual? Give an example for each.

Answer 0

Depressants - decrease activity of the brain, slow response in the central nervous system, slow reactions, impair judgement. E.g. Alcohol

Stimulants - increase activity in the brain by increasing number of neurotransmitters at the synapses, increase reactions, make you feel awake and alert. E.g. Nicotine, caffeine

Analgesics or Painkillers - decrease feeling of pain, some of these drugs work by blocking the nerve impulses to the brain. E.g. Morphine, other narcotics

Hallucinogens - distort what is seen and heard by altering pathways that impulses travel along. E.g. LSD

Question 1

In general, what do drugs do to the body?

Answer 1

Drugs change the way in which chemical react in the body (mostly in the central nervous system) and in turn, affect the way the body behaves.

Question 2

How does smoking affect the body?

Answer 2

Tobacco smoke contains carbon monoxide which combines with haemoglobin, meaning that blood can not transport as much oxygen.
The tar in cigarettes also contains carcinogens which can lead to lung cancer.
Nicotine is addictive.

Question 3

How does alcohol affect the body in the short- and long-term?

Answer 3

Short:
Slows reactions
Blurred vision
Lowers inhibitions

Long:
Alcohol is a poison that the liver usually breaks down, but frequent heavy drinking can damage and kill liver cells, forming scar tissue which blocks blood flow. This is known as cirrhosis.
Toxic substances can build up and damage the rest of the body
Too much drinking can also lead to brain damage

Question 4

Explain the six ways in which pathogens can be spread.

Answer 4

Water - drinking or bathing in dirty water. E.g. Cholera

Food - eating contaminated food. E.g. Salmonella

Air - carried in droplets produced from coughs or sneezes. E.g. Influenza virus

Contact - touching contaminated surface. E.g. Athletes foot

Body fluids - spread by body fluids. E.g. HIV virus

Animal vectors - vectors are animals that spread disease. E.g. Anopheles mosquito transmits malaria, houseflies transmit dysentery

Question 5

What are the physical barriers on the body against pathogens? Explain how they work.

Answer 5

Skin:
If it gets damaged, blood clots quickly to seal cuts and keep microorganisms out.

Respiratory system:
Respiratory tract lined with cilia cells and mucus to catch dust and bacteria before it enters the body. Cilia push the mucus away from the lungs.

Question 6

What are the chemical barriers on the body against pathogens? Explain how they work.

Answer 6

Eyes:
Eyes produce lysozyme which kills bacteria on the eye.

Stomach:
Bacteria that might be on food usually are killed by the hydrochloric acid in the stomach.

Question 7

Define an antiseptic.

Answer 7

A chemical used outside the body to stop diseases from spreading. They are used to clean wounds and on surfaces. Antiseptics prevent infection rather than treat it.

Question 8

Define an antibiotic.

Answer 8

Antibiotics are drugs that are used inside the body to treat patients who are already infected with a bacteria or fungus. They don’t treat viruses.

Question 9

What are the two types of antibiotics and what do they do?

Answer 9

Antibacterials are used to kill bacteria or to stop them from growing. E.g. Penicillin. Bacteria can develop resistance to antibacterials

Antifungals are used to either kill fungal infection or stop them from growing.

Question 10

How do bacteria develop resistance to antibiotics?

Answer 10

Bacteria can mutate and become resistant to an antibiotic. When an antibiotic is used, the non-resistant strain will be killed leaving only resistant bacteria. These will survive and create a new resistant population. This happens when doctors over-prescribe antibiotics or when patients don’t finish a course.

Question 11

Describe the steps of how the sun’s energy gets to a fox.

Answer 11

Plants convert light energy into glucose. Rabbit eats plant and gets some of its energy. The rabbit uses this energy to grow, move, generate heat, etc. and some is stored in the body. A fox then eats the rabbit and gets an even small percentage of its energy. At each level, energy is used by the organisms and can therefore not be passed on to the next trophic level.

Question 12

Define biomass.

Answer 12

Biomass is how much the creatures at each level of a food chain would weigh if you put them together.

Question 13

What is a parasite.

Answer 13

Parasites live in or on a host, taking what they need to survive without giving anything back in return. They usually harm the host in the process.

Question 14

Give a few examples of parasitic animals and plants.

Answer 14

Flees
Head lice
Tapeworms
Mistletoe

Question 15

What is a mutualistic relationship.

Answer 15

Mutualism is where both organisms benefit from the relationship.

Question 16

Give some examples of mutualistic animals and plants.

Answer 16

Oxpeckers and buffalo
Cleaner fish and larger fish
Nitrogen-fixing bacteria and legume plants
Chemo-synthetic bacteria and giant tube worms

Question 17

What is eutrophication?

Answer 17

When too much fertiliser is used on a field, it can run into nearby rivers and lakes, causing excess growth of algae. Other plants start to die due to competition from the algae. Microbes start to grow on the dead plants. These microorganisms use up all of the oxygen in the water and cause fish and other aquatic animals to die.

Question 18

Name some indicator species for air pollution and water pollution.

Answer 18

Air - lichen and blackspot fungi on rose leaves are very sensitive to sulphur dioxide and only live in areas with clean air

Water - stonefly larvae and freshwater shrimp are sensitive to the concentration of dissolved oxygen in the water and therefore indicate clean water. Sludge worms and blood worms on the other hand, are adapted to polluted water and large populations indicate polluted water.

Question 19

Starting with CO2 in the atmosphere, state the steps of the carbon cycle.

Answer 19

1. Photosynthesis in plants takes the carbon dioxide from the air and converts it into carbohydrates, fats and proteins.
2. Animals and other organisms that eat plants take in the carbon and also store it in their bodies.
3. Respiration in both animals and plants puts the CO2 back into the atmosphere.
4. When organisms die, bacteria and fungi break them down, releasing CO2 from respiration.
5. When fossil fuels are burnt, CO2 is also released back into the atmosphere.

Question 20

Starting with nitrogen in the atmosphere, state the steps of the nitrogen cycle.

Answer 20

1. Nitrogen in the atmosphere is in the form of N2 and is very unreactive and can therefore not be used directly by plants or animals. Nitrogen-fixing bacteria in the soil turn the N2 into nitrates that plants can absorb through their roots.
2. Lightening also can turn nitrogen gas into nitrates because of the immense energy in one bolt. It can cause nitrogen to react with oxygen.
3. Nitrogen-fixing bacteria in legume plants’ roots also produce nitrates for the plant to use.
4. Plants use nitrates to make proteins. When animals eat plants, they too get these proteins which are partly made of nitrogen.
5. When organisms die, decomposer bacteria break down the proteins and urea in them into ammonia.
6. Nitrifying bacteria them convert the ammonia into nitrates again.
7. Denitrifying bacteria turn nitrates in the soil back into nitrogen gas in the atmosphere.