GCSE Biology B1

What is the difference between health and fitness?

Fitness is the ability to do physical activity. Health is being free diseases such

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How can fitness be measured?

Strength. Flexibility. Stamina. Agility. Speed

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How is blood transferred through the body?

The blood flows through the arteries which split into capillaries, which take blood to every cell, and then the blood flows back to the heart via the veins

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What is blood pressure measured in?

It is measure in millimetres of mercury. This is written as mmHg

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What measurements make up blood pressure?

Systolic Pressure = when the heart contracts and the blood pressure is at its highest. Diastolic pressure = when the heart relaxes and the blood pressure is at its lowest

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What factors increase blood pressure?

Stress. High alcohol intake. Smoking. Being overweight. Drugs. Genetics

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What decreases blood pressure?

Regular exercise. Eating a balanced diet

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What does high blood pressure cause?

Blood vessels to burst. This can cause damage to the brain- stroke. It can cause damage to kidneys

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What does low blood pressure cause?

Dizziness and fainting as blood supply to brain is reduced. Poor circulation and tissues don't receive all the food and oxygen

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How does smoking increase blood pressure?

Carbon monoxide combines with the haemoglobin in red blood cells, which reduces the amount of oxygen carried. Heart rate has to increase so tissues receive enough oxygen

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How does nicotine in cigarettes increase blood pressure?

Nicotine can increase heart rate as the heart contracts more frequently, increasing the blood pressure

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What is heart disease caused by?

It is caused by a restricted blood flow to the heart muscle

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How is the risk of heart disease increased?

High levels of salt which increases blood pressure. High level of saturated fat in the diet, which leads to a build-up of cholesterol (plaque) in arteries

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What is the narrowing of arteries caused by?

Caused by plaques in the coronary arteries can reduce blood flow to heart. The plaques also make blood clots or thrombosis more likely to happen, which blocks artery

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What are carbohydrates?

They are made up of simple sugars like glucose. Provide energy. Stored in the liver as glycogen or converted to fats

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What are fats?

They are made up of fatty acids and glycerol

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What are proteins?

They are made up of amino acids. Needed for growth and repair. Can't be stored in body

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What does a balanced diet vary according to?

It varies according to factors including age, gender, religion, level of activity, being vegetarian and food allergies

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What does too little protein in the diet cause?

It causes a condition called kwashiorkor

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Why is kwashiorkor more common in developing countries?

Overpopulation: the demand for protein rich food is greater than the amount available. Lack of money: not enough money in agriculture, without best farming techniques its difficult to produce protein rich foods

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What affects EAR?

Body mass. Age. Pregnancy. Breast-feeding

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What are first class proteins?

They contain all the essential amino acids that cannot be made by human body- fish and meat

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What are second class proteins?

Plant proteins that do not contain all the essential amino acids

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Why is BMI not reliable?

It is not always reliable as it cannot distinguish between fat and muscle

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What is malaria caused by?

It is caused by a protozoan called Plasmodium and is carried by mosquitoes, that feed on human red blood cells

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Why are mosquitoes vectors?

They are vectors as they carry the disease without getting it themselves

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Why is plasmodium a parasite and humans hosts?

It is a parasite as it feeds on another living organisms (the host), causing it harm

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Describe how mosquitoes transmit Plasmodium between humans?

Mosquitoes **** infected blood from someone with malaria, and pass plasmodium into another human

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How to reduce the spread of mosquitoes?

Insecticides and mosquito nets. Water where mosquito eggs are can be drained or sprayed with insecticides. Fish can be introduced to eat mosquito larvae

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What is a pathogen?

Pathogens are disease causing organisms

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Types of pathogens?

Fungi- athletes foot. Bacteria- cholera. Viruses- flu. Protozoa-dysentery

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How do pathogens produce the symptoms of an infectious disease?

They damage the body's cells or produce poisonous waste products called toxins

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How does the body protect itself?

By producing antibodies, which lock onto antigens on the surface of pathogens. This kills the pathogen

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What do white blood cells do?

They travel the body patrolling for pathogens.

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What do WBCs do when they come across a microorganism?

Engulf foreign cells and digest them. Produce antitoxins- which counter the effect of any toxins produced by pathogen. Produce antibodies

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What are memory cells (T-lymphocyte cell)

WBCs that stay in the blood after the pathogen has been fought off. If a person is infected again, the cells will remember and produce antibodies to kill it- natural immunitity

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What is the process of immunisation?

Injecting harmless pathogen carrying antigens into body. These trigger a response by WBCs, producing antibodies. Memory cells remain in body, providing long-lasting immunity to that disease

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What is passive immunity?

Where you use antibodies made by another organism, e.g. antibodies passed on from mother to baby through breast feeding. It has a quick but short-term effect

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What is active immunity?

This is where the immune system makes its own antibodies after being triggered by pathogen. Slow but long-lasting effect

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What are the benefits of immunisation?

Stops you from getting ill. Disease won't spread easily if most people are immunised

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Side effects of immunisation?

Swelling. Redness at site of injection

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What is cancer caused by?

Body cells dividing out of control, forming a tumout

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What is a benign tumour?

Benign tumour cells divide slowly and are harmless

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What is a malignant tumour?

A malignant tumour is where cells display uncontrolled growth and may spread. Can be fatal

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What reduces the risk of cancer?

Not smoking reduces the risk of lung cancer, Using sunscreen reduces the risk of skin cancer

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What are antibiotics?

They are drugs that kill bacteria without killing body cells. It destroys a pathogen

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What has excessive use of antibiotics resulted in?

It has resulted in resistance forms of bacteria being more common than non-resistant forms

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What are antivrals?

They are drugs that are used to treat viral infections, and stop viruses from reproducing. It slows down the pathogens development

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What is new drugs tested on before human trials?

Computer models. Human tissue. Animals

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How are computer models used to test drugs?

Stimulate a humans response to a drug so animal does not need to be tested. It is not as accurate as directly testing on live organims

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Why is testing on human tissue not that efficient?

This is because human tissue cannot be used to test drugs that affect multiple body systems

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How is the drug tested on animals?

It has to be tested on two different mammals. Some think it is cruel but others believe it is the safest way to ensure a drug is not dangerous

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What is a placebo?

A placebo is a harmless pill. Placebos are used as a comparison in drug testing so the effect of a new drug can be assessed

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What occurs in a blind trial?

The patient does not know whether they are receiving a new drug or a placebo

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What occurs in a double blind trial?

Neither the patient or the doctor know which treatment is being used

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What is a depressant?

E.g. alcohol and solvents. They decrease they activity of the brain which slows down the responses of the nervous system, causing slow reactions and poor judgement of distance

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What is a stimulant?

E.g. nicotine, ecstasy and caffeine. They increase the activity of the brain making you feel alert. They are used to treat depression

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What is a painkiller?

E.g. aspirin and paracetamol. Mild painkillers work by reducing the number of painful stimuli at the nerve endings near an injury

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What is a performance enhancer?

E.g. anabolic steroids. Athletes take these to build muscle and allow them to train harder

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What is a hallucinogen?

E.g. LSD. They distort what is seen and heard by altering pathways that the brain sends messages along

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What do class A, B and C drugs include?

A:Heroin, LSD, Ecstasy and Cocaine. B:Cannabis and Speed. C: Anabolic steroids and tranquilisers

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What does drinking excessive alcohol cause?

Cirrhosis of the liver- liver breaks down toxic chemicals such as alcohol. This causes the death of liver cells forming scar tissue that stops blood reaching the liver. Dangerous substances build up

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What does being drunk lead to?

Impaired judgement, poor balance, slurred speech, blurred vision, increases risks of accidents and increases time taken to react

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What does carbon monoxide in cigarettes do?

It reduces teh capacity of oxygen that the blood can carry. If the heart doesn't receive enough oxygen it can lead to a heart attack

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What does tar in cigarettes do?

It collects in the lungs, forming lung, throat, mouth or oesophageal cancer. Tar contains toxic chemicals like carcinogens, which cause mutations in DNA, causing cell division to go out of control

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What is a smokers cough a result of?

Dust and particulates in cigarette smoke collecting and irritating the epithelial lining. Mucus not being moved by cilia

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How is emphysema caused?

The lungs lose their elasticity causing emphysema

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What does smoking damage babies?

It can cause low birth weight and low oxygen in the blood of pregnant women can deprive foetus of oxygen leading to small baby at birth

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What does the cornea do?

Refracts light into the eye

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What does the iris do?

Controls how much light enters the pupil

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What does the lens do?

It also refracts light, focusing it onto the retina

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What does the retina contain?

Receptors called rods and cones which detect light. Rods can't sense colour and cones are sensitive to different colours but not good in dim light

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What does the optic nerve do?

It carries impulses from the receptors to the brain

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What is accommodation?

This is where the eye focuses light by changing the shape of the lens because it is elastic

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What happens when looking at distant objects?

Ciliary muscles relax. Suspensory ligaments tighten. Lens has a less rounded shape so light is refracted less

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What happens when looking at near objects?

Ciliary muscles contract. Suspensory ligaments slacken. Lens regain a more rounded shape. Light is refracted more

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What is red-green colour blindness caused by?

Caused by a lack of specialised cells in the retina

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What happened when people are long-sighted?

The eyeball is too short and lens too thin, so image is focused behind the retina. Convex lens to correct it

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What happens when people are short-sighted?

The eyeball is too long and lens too rounded, so the lens refracts too much light, so image is focused in front of retina. Concave lens to correct

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What is binocular vision?

It helps you judge distance by comparing the images from each eye; the more different they are, the nearer the object

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What does the central nervous system consist of?

Brain and spinal cord. It is made up of different nerve cells (neurones), sensory neurones and motor neurones

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What happens when there is a change in environment (stimulus)?

Sensory neurones carry the information from receptors to CNS. CNS then send information to effector along a motor neurone. Effector responds

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How does the nervous system allow quick responses?

It uses electrical impulses. The reflex actions are automatic, the conscious brain is not involved in a reflex arc

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What is the pathway for a spinal reflex?

Receptor-Sensory neurone-Relay neurone-Motor neurone-Effector

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How do neurones transmit information?

As electrical impulses, which are passed along the axon of the cell

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How are neurones adapted?

Have branched endings (dendrites) to pick up impulses. Insulator sheath along axon, which speeds up impulses. They're long which speeds up impulses

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What is a synapse?

The gap between neurones is called a synapse

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What does the arrival of an impulse trigger?

The release of a transmitter substance, which diffuses across synapse. Transmitter substance binds with receptor molecules in next neurone causing impulse to continue

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What do depressants cause?

They block the transmission of nerve impulses across synapses by binding with receptor molecules in the membrane of the receiving neurone

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What do stimulants cause?

They cause more neurotransmitter substances to cross synapses

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What is homeostasis?

Homeostasis is maintaining a constant internal environment. It involves balancing inputs and outputs

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What does homeostasis include?

Automatic control systems which keep the levels of temperature, water and carbon dioxide steady, which ensures cells work at optimum levels

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How are negative feedback controls used in homeostasis?

They act to cancel out changes in environment such as a decreasing temperature level

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How is blood temperature monitored?

It is monitored by the hypothalamus gland in the brain

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What can high temperature cause?

Heat stroke- skin becomes cold and clammy and pulse is rapid and weak. Dehydration- loss of too much water

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What happens when you are too hot?

Hairs lie flat. Lots of sweat is produced, when it evaporates it uses heat from the skin. Vasodilation

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What is vasodilation?

When the body is too hot small blood vessels in the skin dilate and so blood flow increases, bringing more blood to the surface, where it loses heat

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What can low temperatures cause?

Hypothermia. Frostbite. Could stop enzymes from working

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What happens when you are too cold?

Hairs stand to trap an insulating layer of air. Very little sweat is produced. Vasoconstriction

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What is vasoconstriction?

When the body is too cold small blood vessels in the skin constrict and so less blood flows through them, reducing heat loss

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What controls blood sugar levels?

Hormone called insulin. Insulin is added when blood glucose levels are high

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What is type 1 diabetes?

This is when the pancreas does not produce any insulin, blood glucose levels rise

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How is type 1 diabetes treated?

It is treated by having doses of insulin and having a carefully controlled diet

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What does injecting insulin do?

Makes the liver remove the glucose as soon as it enters the blood from the gut. This stops the level of glucose in blood getting too high

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What does the amount of insulin injected depend on?

It depends on the persons diet and how active they are. This is because vigorous exercise removes glucose from blood

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What is type 2 diabetes?

It is caused by the body producing too little insulin or the body rejecting to it

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How is type 2 diabetes controlled?

It can be controlled by avoiding foods rich in simple carbohydrates or sugars

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What is auxin?

Auxin is a plant hormone which controls growth. It moves through the plant in solution

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Where is auxin made?

Auxin is made in the root and shoot tip. It promotes growth in the shoot but inhibits growth in the root

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What is phototropism?

Plants response to light

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What is geotropism?

Plants response to gravity

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Explain what is meant by shoots being positively phototropic?

When shoot tip is exposed to light, it accumulates more auxin on the side in the shade. This makes the cell elongate faster on the shaded side, so the shoot bends towards light

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Explain what is meant by shoots being negatively geotropic?

When a shoot is growing sideways, gravity produces an unequal distribution of auxin in the tip with more auxin on the lower side

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Explain what is meant by roots being negatively phototropic?

Root is exposed to light, more auxin accumulates on the shaded side. The auxin inhibits cell elongation on the shaded side, root bends down back into the ground

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Explain what is meant by roots being positively geotropic?

In a root extra auxin inhibits growth, this means the cells on top elongate faster and root bends downwards

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Uses of Plant Hormones?

Selective weedkillers. Rooting powder to increase root growth of cuttings. Controlling ripening of fruit. Controlling dormancy in seeds

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What does the nucleus contain?

It contains genetic material in the form of chromosomes. Chromosomes carry genes that control the development of different characteristics

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What is an allele?

Alleles are different versions of the same genes

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When are dominant and recessive alleles expressed?

Dominant alleles are expressed when present but recessive alleles are expressed in the absence of dominant alleles

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What chromosomes do females and males have?

Females have identical sex chromosomes called **, males have different chromosomes called XY

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How is genetic variation caused?

By mutations- new characteristics increasing variation. Rearrangements of genes during the formation of gametes. Fertilisation- zygote with alleles from mother and father

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What is meant by homozygous?

It means having identical alleles

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What is meant by heterozygous?

It means having different alleles

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What is meant by genotype?

Genetic makeup- the alleles you have for a particular gene

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What is meant by phenotype?

Characteristics that these alleles produce

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What are inherited disorders caused by?

Faulty genes

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What ethical issues are raised by deciding to have a genetic test?

Knowing the risk of passing on an inherited disorder. Terminating the pregnancy

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GCSE Biology B1

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