core biology gcse

Question	Answer
What main characteristic do organisms in the chordata phylum have in common?	They are all vertebrates
What do all vertebrates have in common?	They all have an internal rod like structure. e.g backbone
What does oviparous mean? Name a group of vertebrates that are oviparous.	It means that they lay eggs and Birds.
What is the name of the offspring of two different species?	A Hybrid
In the binomal system each organism is given a two part name. What does each part refer to?	1st part the genus. 2nd part the species
Other than the environment what causes variation?	Genetics
What is a) continuous variation b) discontinuous variation	continuous variation = when it can be any amount within a range. discontinuous variation = when there are two or more distinct categories
Give an example in humans of both continuous and discontinuous variation.	Continuous - height, hand span discontinuous - eye colour, blood type
Explain two ways in which deep sea fish have adapted to their environment.	Often have huge mouths to catch prey, huge eyes which are adapted to the dark and long feelers to help them locate prey.
Explain two ways in which polar bears have adapted to living in polar regions.	They have a compact round shape which reduces heat loss They have big feet to spread their weight which stops them breaking thin ice. White fur for camouflage Thick layer of blubber for insulation.
Explain darwins theory of natural selection.	Drawins theory is the idea of survival of the fittest meaning tat only the best adapted organism will survive to produce fertile offspring and evolve.
Give three ways that the scientific community validate evidence.	First they publish their work in scientific journals so other scientists can check the work and make sure its reliable. Then it has to be peer reviewed. Then scientific conferences are held so the evidence is shared and discussed.
What is speciation? Explain how geographical isolation can lead to speciation.	Speciation is the development of a new species. Isolation is where populations of the same species are separated due to a physical barrier e.g earthquakes, floods... conditions on either side will be different and eventually individuals from the different populations will have changed so much they will no longer be able to reproduce fertile offspring. The groups will become separate species.
How many pairs of chromosomes are there in a normal human cell nucleus.	23 pairs
What is an allele?	An allele is a different version of the same gene
What is meant by an organism being heterozygous? What about homozygous?	Heterozygous = the two alleles in the gene are different Homozygous = the two alleles in the gene are the same
Describe the difference between a recessive allele and a dominant one.	For an organism to display a recessive characteristic , both its alleles must be recessive (cc) For it to display a dominant characteristic the organism can be either CC or Cc because the dominant allele over rules the recessive one.
What are the symptoms of cystic fibrosis?	Breathing difficulties, lung infections, malnutrition and fertility problems.
Give two symptoms of sickle cell anameia.	Tiredness, painful joints, muscles, fever and anameia
Is the allele for sickle cell anemia dominant or recessive?	Recessive
What is homeostasis?	Maintaining a stable internal environment
Describe how body temperature is reduced when your too hot.	- Erector muscles relax so hairs lie flat -lots of sweat is produced to cool you down -blood vessels close to the surface of the skin - called vasodilation allowing more blood to flow near the surface and transfer more heat.
Describe how body temperature is increased when you are too cold.	-Erector muscles contract so hairs stand up. - very little sweat is produced -blood vessels near the surface of the skin constrict- called vasoconstriction meaning less blood flows near the surface of the skin so lead heat is transferred to the surroundings.
What are hormones?	Chemical messengers sent in the blood
How do hormones travel around the body?	They travel at the speed of blood
What is the name given to chemicals found at synapses?	Neurotransmitters
List four main differences between nerves and hormones...	Nerves - 1) very FAST message 2) act for a very SHORT time 3) act in a PRECISE AREA 4) ELECTRICAL message Hormones - 1) SLOWER message 2) act for a LONG TIME act in a more GENERAL way 4) CHEMICAL message
List the 5 sense organs and the receptors they each contain.	1) eyes - contain light receptors 2) Ears - sound receptors 3) Nose- smell receptors 4) Tongue - taste receptors 5) skin - touch and temperature change
What does CNS stand for	Central Nervous System
What does the CNS consist of?	Effectors - muscles and glands Motor neurons - many short dendrons and one long axon carry nerve impulses from the CNS to the effector Relay neurons - short dendrons and a long axon carry nerve impulses from sensory neurons to motor neurons. Sensory neurons - long dendrons and short axons carry nerve impulses in the sense organs to the CNS.
What does the CNS do?	Coordinates a response to a change in your environment (stimulus)
What is the purpose of a reflex?	Reflexes help prevent injury and a reflex arc goes through the central nervous system.
Describe the pathway from stimulus to response.	1) When a stimulus is by detected by receptors impulses are sent along a sensory neurone to the CNS. 2) In the CNS the sensory neurone passes a message along a relay neurone 3) relay neurones relay the info to a motor neurone. 4) the impulses travel along the motor neurone to the effector 5) The muscle contracts and moves away
Describe what happens when blood glucose level is 1) too high 2) too low	1) When it is too high insulin is added. 2) When it is too low glucagon is added
Describe the main way which type one diabetes can be controlled.	When the pancreas produces little or no insulin. Controlled by avoiding foods rich in carbs i.e sugars. and Injecting insulin.
What does it mean if a person is resistant to insulin?	It means they have type two diabetes and that their pancreas produces little or no insulin due to being obese.
What is the name given to a plants growth response to light?	Tropism
What is auxin?	Auxin is a plant hormone which controls growth at the tips of shoots and roots.
Shoots are positively phototropic. What does that mean?	When a plant tip is exposed to light, more auxin accumulates on the side thats in shade. This makes the cells grow faster meaning they grow upwards.
Roots are positively gravitropic. Explain the role of auxin in this response.	Meaning roots grow downwards. When a root grows sideways, gravity produces an unequal distribution of auxin in the tip with more on the lower side.
What is gibberellin?	A type of plant growth hormone which stimulates plant stems to grow
List three things which gibberellin stimulates in plants	1) seed germination 2) stem growth 3) flowering
Describe how plant hormones are used as selective weed killers.	- selective weed killers have been developed from plant growth hormones which only affect broad-leaved plants. -they disrupt their normal growth patterns which soon kills them but leaves grass and crops untouched.
What is growing cuttings with rooting powder?	- a cutting is part of a plant that has been cut off like a branch with a few leaves on it. - normally the cuttings wont grow in soil but if you add rooting powder which contains growth hormones they will produce roots and start growing as new plants. -this enables producers to make lots of clones of a good plant very quickly.
How does a stimulant drug work? Give two examples of stimulants	They increase the activity of the brain and increase the speed of reactions.
How does a depressant work?	These decrease the activity of the brain and decrease reaction time.
Describe the harmful effects of 1) nicotine 2) tar 3) carbon monoxide	1)Addictive 2) a chemical that leads to cancer 3) causes the blood to carry less oxygen.
State two long term effects of drinking too much alcohol.	1) Causes the death of liver cells which forms scar tissue which blocks blood flow in the liver. 2) Brain damage
What is a pathogen?	microorganisms that cause disease e.g bacteria, protoza, fungi and viruses.
What is a vector?	An animal that spreads disease.
State 4 ways pathogens can be spread and give an example of each.	1) Water - drinking or bathing in dirty water e.g cholera 2) Food - eating contaminates food e.g samonella 3) Air - produced by coughs or sneezed e.g influenza virus 4) Contact - spread by body fluids such as blood e.g HIV
Name one chemical and one physical barrier that defend against pathogens.	Physical - SKIN Chemical - EYES
What do plants produce to defend themselves against bacteria?	They can produce chemicals such as tea tree.
What are antiseptics?	Used outside the body to stop disease spreading. Chemicals that destroy bacteria or stop them growing.
Name two types of antibiotics.	Anitbacterials e.g penicillin used to treat bacterial infections. Antifungals e.g nystatin used to treat fungal infections
Name one type of bacteria that has developed resistance to certain antibiotics.	MRSA causes serious wound infections and is resistant to the powerful antibiotic methicillin.
Why shouldn't your doctor give you antibiotics for a mild infection?	You can become resistant to antibiotics.
Where does the energy in a food chain originate? What happens to the energy?	Energy in a food chain originates from the sun. Energy is lost at each stage.
Why are pyramids of biomass always pyramid shape?	Each time you go up a level on the pyramid the mass of organisms goes down because most of the biomass (energy) is lost.
What is the difference between a parasitic and mutalistic relationship?	Parasitic = take without giving anything in return. Mutalisitic = both organisms gain
Give examples of parasites	- Fleas - Head lice - tapeworms -mistletoe
Give examples of mutalistic relationships	- oxpeckers that live on buffalo. -cleaner fish that live on larger fish
Give three ways that increasing human population has a greater effect on the environment.	- more and more waste produced - more and more pollutants - raw materials including non renewable energy is being used up
Explain what eutrophication is.	When fertilisers help crops but harm water life. Problems start when rich fertiliser finds its way into rivers, lakes and seas. The result is eutrophication- too many nitrates involving the death of most of the plant and animal life in the water.
Give two advantages and two disadvantages of recycling...	Advantages - Uses up less of the earths natural resources, creates less pollution. Disadvantages - the equipment can be expensive and it can be time consuming to sort out.
What does it mean if you find stonefly larve or freshwater shrimp in a river/	Indicates that the water is clean
If the river is polluted what will you find in it?	Blood worm or sludgeworm
Explain how lichen can be used as an indicator of air pollution.	The number of lichen in a particular area will indicate how clean the air is (e.g if the air is clean then lots of lichen)

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