Biology Unit 1 Revision Cards

Why do we have a nervous system?

So we are able to respond to a stimulus.

What is a stimulus?

A stimulus is a change in the environment.

What is a receptor?

A cell that detects a stimulus.

What are the special features of a nerve cell?

They are long - this is so information can travel over long distances.

They have branches - this is so information can travel to more than one place.

What are the two nervous actions?

Reflex - This means that the brain/co-ordinater is not involved in the action; it is involuntary.

Concsious - The brain/co-ordinater is involved in the action

What is a synapse? How does it work?

A synapse is the gap between two nerve cells/neurones. A synapse is made up of a chemical called a neuro - transmitter. This allows a chemical impulse to diffuse across the synapse from one neurone to another.

What is a pathogen?

A harmful microbe that can cause disease.

What are the three types of pathogen?

Viruses, bacteria and fungi.

What do bacteria and fungi do?

They replicate outside of cells and make poisonous toxins.

What do viruses do?

Virus exist inside a host cell. They use the host cell DNA to replicate . They can damage the cell and make toxins.

What are some of the ways our body protects itself?

Lymphocytes produce white blood cells specific to the pathogen. The antibodies recognise the pathogens as foreign because they have antigens. The antibodies attatch to the antigens of the pathogen. Phagocytes then engulf and destroy the pathogens. Furthermore, white blood cells can produce anti-toxins.

How can pathogens change?

A mutation in the DNA can happen.

What are the advantages of being vaccinated against a disease?

You become immune to that disease because your white blood cells know what antibodies are needed for the pathogen. Mass vaccination means that a virus can be irradicated e.g. small pox.

What are the disadvantages of being vaccinated against a disease?

The vaccination is completely useless against a mutated form of the virus or pathogen. HIV constantly makes mistakes when replicating meaning that it is always mutating and, therefore a vaccination is useless against it.

What is a vaccination?

A person is injected with a weakened or dead form of the pathogen. This stimulates lymphocytes to produce specific anti-bodies. When the person is next exposed to the pathogen the lymphocytes will produce specific anti-bodies more rapidly preventing disease.

What is the main idea of evolution?

Organisms continuously change over a long period of time. All life on Earth has developed from one single life form which arrived 3,000,000,000 years ago.

What is natural selection?

The better adapted a living thing is to its environment the more likely it is to survive. These living things are likely to reproduce and, therefore the favourable genes will be passed on to offspring. It is also referred to as, 'survival of the fitest'.

Who came up with the theory of evolution?

Charles Darwin.

What was 'Lamark's' theory?

Living things change over time.

Characteristics inherited in an individuals life time can be inherited by their offspring.

What are gateway drugs?

A drug that leads you to form a habit. It may lead to the use of other addictive drugs.

What are withdrawal symptoms?

A disturbance that can be physical, physcological or both. It can be experienced by drug addicts when deprived of drugs.

What is addiction?

When a person is unable to stop taking particular substances or doing particular things.

What is addiction?

When a person is unable to stop taking particular substances or doing particular things.

What is addiction?

When a person is unable to stop taking particular substances or doing particular things.

What is addiction?

When a person is unable to stop taking particular substances or doing particular things.

What is addiction?

When a person is unable to stop taking particular substances or doing particular things.

What is addiction?

When a person is unable to stop taking particular substances or doing particular things.

What is addiction?

When a person is unable to stop taking particular substances or doing particular things.

What are the ways of classifying drugs?

Some drugs are legal and others are not. Some are prescribed or given over the counter.

What are the parts of a cigarette and what do they do?

Nicotine - This is the drug; it is the addictive part of the cigarette.

Tar - This is carcynogen and causes cancer.

Carbon-monoxide - This joins to the haemoglobin and reduces the amount of oxygen that can travel around the body for respiration.

What parts of the body does alcohol affect most?

The liver and the brain.

How long does it take for the liver to break down alcohol?

It takes the liver approximately 1 hour to break down 1 unit of alcohol.

What is sexual reproduction?

The joining of the sperm cell and egg cell to create a fertilized egg.

How many chromasomes do the sperm and egg cells and a zygote have?

Sperm and egg - 23 single chromasomes each

Zygote - 46 single chromasomes, 23 pairs.

What is asexual reproduction?

The DNA of 1 cell replicates. The cell membrane splits and the cell divides into 2 genetically identical cells/clones.

What is tissue culture?

Tissue culture - A sample from a plant is put in an agar growth dish with nutrients and auxins to help it grow. The samples develop into plantlets which are planted in compost to grow.

What is embryo transplantation?

Embryo transplantation - Sexual reproduction takes place leaving fertilized eggs. The cells divide and are implanted into surrogates. New animals are born all identical to eachother but show variation from their parents.

What is cloning adult cells?

A cell is taken from the animal. The nucleus is removed and saved. An egg cell is taken from the second animal. The nucleus is removed. The nucleus from the first animal's cell is put into the nucleus of the second animal's cell. The new cell is stimulated by an electric shock and implanted into a surrogate mother. The new animal is a clone of the first animal.

What is taking cuttings?

A small cutting of a plant is grown in the right conditions producing a small new plant. This produces plants quicker and cheaper. The cuttings will be identical to the original plant.

What needs to be present for decay to take place?

Microbes. Oxygen - for the microbes to respire. The appropriate temperature for enzymes. Moisture.

How does putting holes in a compost bin speed up the rate of decay?

The holes allow for more oxygen in the bin for microbes to respire.

What is a hormone?

A hormone is a chemical messenger. They travel in the blood plasmaand are produced in glands. They are part of the endocrine system and act on target organs.

What hormones are used to control the menstrual cycle?

FSH, Oestrogen and LH.

How can hormones be used to control fertility?

They are used in fertility treatment in order to increase chances of fertility.

They are used in contraseption in order to decrease chances of fertility.