Adaptations for survival
Adaptations for a hot environment...
- plants with no leaves
- plants that can dig deep for water
- light coloured skin
- short/no fur
- thick skin
- able to go without water for a long time
- store water
- padded feet
- doesn't perspire much
- ability to burrow
- large ears to lose heat
- good fat storage
Adaptations for survival continued...
Adaptations for a cold environment...
- Thick fur
- Good fat storage
- Small ears
- Most animals are big
- Normall have good camoflage
- Big feet so don't sink in snow
Some micro-organisms are known as extremophiles - they're adapted to live in seriously extreme conditions like super hot volcanic vents, in very salty lakes or at high pressure on the sea bed.
Indicator species and environmental change
Environmental change is caused by different factors:
- A change in the occurence of infectious disease
- A change in the number of predators
- A change in the number of prey or availability of food sources
- A change in the number or types of competitors
- A change in the average temperature
- A change in the rainfall
- A change in the level of air or water pollution
Indicator species = Different species that indicate how clean the whole area is.
A balanced diet does a lot to keep you healthy. For good health, your diet must provide the energy you need. But that's not all. Because the different food groups have different uses in the body, you need to have the right balance of foods as well.
- Carbohydrates release energy
- Fats to keep warm and release energy
- Protein for growth, cell repair and cell replacement
- Fibre to keep your digestive system moving smoothly
- Tiny amounts of vitamins and minerals to keep skin, bone and everything generally healthy
You need energy to fuel the cemical reactions in the body that keep you alive. These reactions are called your metabolism, and the speed at which they occur is your metabolic rate. Physically bigger people are likely to have higher metabolic rate than smaller people. Men tend to have a slightly higher rate than women. Regular exercise can boost your resting metabolic rate because it builds muscle.
When you exercise, you obviously need more energy so your metabolic rate goes up during exercise and stays high for some time after. So people who have more active jobs need more energy on a daily basis.
Factors affecting health
You health is affected by having an unbalanced diet...
People whose diet is badly out of balance are said to be malnourished. Malnourished people can be fat or thin, or unhealthy in other ways:
Eating too much can lead to obesity.. excess carbohydrate or fat in the diet can lead to obesity. Obesity is a common disorder in developed countries - it is defined as 20% or more over maximum body mass. Hormonal problems can lead to obesity, though the usual cause is a bad diet, overeating and a lack of exercise. Too much saturated fat in your diet can increase your blood cholesterol levels. Eating too much salt can lead to high blood pressure and heart problems.
Eating too little can also cause problems. Some people suffer from lack of food, particularly in developing countries. The effects of malnutrition vary depending on what foods are missing from the diet. But problems commonly include slow growth, fatigue, poor resistance to infection and irregular periods in women. Deficiency diseases are caused by a lack of vitamins or minerals. For example, a lack of vitamin C can cause scurvy, a deficiency disease that causes problems with the skin, joints and gums.
Factors affecting health continued..
Not getting enough exercise
Exercise is important as well as diet - people who exercise regularly are usually healthier than those who don't. Exercise increases the amount of energy used by the body and decreases the amount stored as fat. it also builds muscle so it helps to boost your metabolic rate. So people who exercise are less likely to suffer from health problems such as obesity. However, sometimes people can be fit but not healthy - e.g. you can be physically fit and slim, but malnourished at the same time because your diet isn't balanced.
It's not just about what you eat and how much exercise you do - your health can depend on inherited factors too. Some people may inherit factors that affect their metabolic rate e.g. some inherited factors cause an underactive thyroid gland, which can lower the metabolic rate and cause obesity. Other people may inherit factors that affect their blood cholesterol level. Cholesterol is a fatty substance that's essential for good health - it's found in every cell in the body. Some inherited factors increase blood cholesterol level, which increases the risk of heart disease.
There are 2 main types of pathogen; bacteria and viruses.
Bacteria are very small cells which can reproduce rapidly inside your body. They make you feel ill by doing 2 things: damaging your cells and producing toxins (poisons).
Viruses are not cells - they're much smaller. They replicate themselves by invading your cells and using the cells' machinery to produce many copies of themselves. The cell will usually then burst, releasing all the new viruses. This cell damage is what makes you feel ill.
Your body has a defence system also. Your skin, plus hairs and mucus in your respiratory tract stop a lot of things getting inside your body. And to try to prevent microorganisms getting into your body through cuts, small fragments of cells (platelets) help blood clot quickly to seal wounds. If the blood contains low numbers of platelets then it will clot more slowly. But if something does get through, your immune system kicks in. The most important part is the white blood cells. They travel in your blood and crawl into every part of you, constantly patrolling. They have 3 lines of attack.
1) Consuming them. 2) Producing antibodies. 3) Producing antitoxins.
When you're infected with a new microorganism, it takes your white blood cells a few days to learn how to deal with it. By this time you can feel ill.
Vaccinations involve injecting small amounts of dead or inactive microorganisms. These carry antigens, which cause your body to produce antibodies to attack them - even though the microorganism is harmless. But if live microorganisms of the same type appear after that, the white blood cells rapidly mass-produce antibodies to kill off the pathogen.
Vaccines have helped control lots of infectious diseases that were once common in the UK. Big outbreaks of disease (epidemics) can be prevented if a large percentage of the population is vaccinated.
Vaccines don't always work. You can sometimes have a bad reaction the the vaccine.
Fighting disease - Drugs
Some drugs just relieve symptoms, others cure the problem.
Painkillers just relieve the pain, they don't get rid of it. Antibiotics work differently, they actually kill the bacteria causing the problem without killing your own body cells. Different antibiotics kill different types of bacteria. Antibiotics don't kill viruses. Viruses reproduce using your own body cells which makes it difficult to develop drugs that destroy the virus without killing the body cells.
Bacteria can become resistant to antibiotics.
Bacteria can mutate - sometimes this causes them to be resistant to an anticiotic. If you have an infection, some of the bacteria may be resistant to antiobiotics. This means that when you treat the infection, only the non-resistant strains of bacteria will be killed. The individual resistant bacteria will survive and multiply and the population will increase. This is an example of natural selection. This resistant strain can cause a serious infection.