B1

These cards will help to revise Biology 1 higher

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  • Created by: Kate
  • Created on: 14-05-12 17:43

Alcohol effects

- Alcohol is broken down by enzymes in the liver

- Some of the substances are toxic

- Drinking too much alcohol over a long time causes scar tissue in the liver

- This stops the blood entering the liver (cirrhosis)

- Alcohol causes dehydration which can damage other cells eg. the brain

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Smoking effects

- Smoking = heart disease - carbon monoxide combines with haemoglobin and causes the blood to not carry as much oxygen which can cause a heart attack

= Cancer - tar collects in the lungs. the toxic chemicals can cause mutations in the DNA which causes unusual cell division making malignant tumours

= Smokers cough - it damages the cilia which lines the trachea, bronchi and bronchioles so more mucus is produced which cannot be cleared by the cilia so you get a smokers cough

= Low weight babies - the carbon monoxide prevents the needed amount of oxygen getting to the baby

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The central nervous system

- The CNS consits of the brain and spinal cord

- It is made up of sensory, relay and motor neurones

- When there is a stimulus (change in environment) the sensory neurone carries information from receptors to the CNS

- The CNS sends information to an effector and along a motor neurone

- The job of the CNS is to coordinate the information

- The order = stimulus, receptor, sensory neurone, CNS, Motor neurone, effector, response

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Reflex actions

- The nervous system uses electrical impulses to allow very quick resposes

- Reflex actions are automatic and you complete the reaction before you realise

- The sensory neurone connects to the relay neurone in the spinal cord which links directly to the motor neurone

- Reflex actions often have a protective role to stop you from harming yourself

- Order of reaction = bee stings finger, stimulation of the pain receptor, message travels along the sensory neurone, message passed along a relay neurone, message travels along a motor neurone and then the message reaches the muscle and it moves away from the bee

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Neurones

- Electrical impulses are passed along the axon which has a protective sheath that acts as an electrical insulator that speeds up the electrical impulse

- Neurones have branched endings (dendrites) so they can connect with many neurones

- The axons are long so it speeds up the process

- The electrical impulse triggers the release of transmitter chemicals which defuse across the synapse

- The chemicals bind to the receptor molecules in the membrane of the next neurone which sets of a new electrical impulse

- Stimulants increase the amount of transmitter chemicals increasing the frequency that the electrical impulses cross the synapse at

- Deppresants bind to the transmitter chemicals blocking the electrical impulse

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Homeostatis

- it is maintainig a constant internal environment

- It includes the level of CO2, water and body temperature

- Negative feedback allows the body to counteract the problem eg, if you are too hot the negative feedback would tell the body to sweat and cool you down

- Enzymes have an optimum temperature of 37'C but if it gets above that they are denatured

- When you are too hot - hairs lie flat, lots of sweat is produced and blood vessels close to the surface widen (vasodilation)

- When you are too cold - hairs stand on end, very little sweat is produced, the blood vessels near the surface constrict (vasoconstriction) and you shiver

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Insulin

- Vigorous exercise and respiration removes glucose from the blood

- Insulin is created in the pancreas and released into the blood when there is too much glucose and takes it to the liver where it is turned into glycogen

- When there is too little glucose in the blood the pancreas dosen't release any insulin and the glycogen stored in the liver is turned back into glucose and put back into the blood

- Insulin is a hormone and travels in the blood so it is not as fast as electrical impulses

- Type 1 diabetes - the body doesn't produce any insulin so they have to inject insulin into the body and control their diet

- Type 2 diabetes - the body is resistant to insulin so they have to stay away from carbohydrate rich food and monitor their diet

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Plant hormones and growth

- Auxins are plant hormones which are in the shoots and roots

- Auxins promote growth in the shoot but inhibits it in the root

- Shoots are positively phototropic (grow towards light) - the side in the shade has more auxins which elongates it and moves it towards the sun

- Shoots are negatively geotropic (grow away from gravity) - when a shoot grows sideways the auxins are on the lower side so they drow faster and go upwards

- Roots are positively geotropic (grow towards gravity) - the auxins will be on the lower side but the extra auxins inhibit growth so the roots grow downwards

- Roots are negatively phototropic (grow away from light) - when roots have light the auxins move to the shaded side which inhibits auxin elongation so it grows downwards

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Commercial use of plant hormones

- Weed killers - most weeds are broad leaved compared to other plants which are narrowed leaved - selective weedkillers have been designed to only kill broad leaved plants - it dissrupts the normal growing pattern causing death

- Rooting powder - a cutting is planted into the soil but it won't grow normally so they add rooting powder which contain plant hormones that promote growth - It allows clones of plants to be made

- Controlling the ripening of fruit - they are used to delay the ripening whilst they are being transported to the shops - it alows them to be picked whilst still unripe preventing damage to the plant - when they get to the shop they add ripening hormones so that they will be perfect for the shelves of supermarkets

- Dormancy - many seeds won't germinate untill the conditions are right - a hormone called gibberellin breaks the dormancy and allows them to germinate - the hormone allows crops to be grown all year where they normally would not be able to

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Genes and chromosones

- Most cells in the body have a nucleas which stores all of the genetic information in form of chomosones

- In animals chromosones are in pairs but the number of pairs vary with each species such as humans with 23 pairs

- Chromosones carry genes which control the development of different characteristics

- A gene is a short length of the chromosone

- Which is quite a long length od DNA

- The DNA is coiled up in the arms of chromosones

- There are differebt versions of the same gene which give versions of characteristics like blue or brown eyes

- The different versions of the same genes are called alleles instead of genes

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Genes and chromosones

- Most cells in the body have a nucleas which stores all of the genetic information in form of chomosones

- In animals chromosones are in pairs but the number of pairs vary with each species such as humans with 23 pairs

- Chromosones carry genes which control the development of different characteristics

- A gene is a short length of the chromosone

- Which is quite a long length of DNA

- The DNA is coiled up in the arms of chromosones

- There are differebt versions of the same gene which give versions of characteristics like blue or brown eyes

- The different versions of the same genes are called alleles instead of genes

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Genetic variation

- Gamete formation - they are sperm and egg cells - they are made from 23 pairs of chromosones in each pair where there is one chromosone that is inherited from mum and dad - when the body cells split to form gametes the chromosones are also split up with half the number of body cells in each - some of your dad's chromonsones are grouped with your mum's - this leads to variation in the next generation

- Fertilisation - it is when the sperm and egg join together to made the full 46 chromosonesbut fertilisation is random so you don't know what the characteristics will be

- Mutations - change the genetic code which creates new characteristics

- Most features are determined by genes and environment:

=Health - some people are more likely to get diseases but lifestyle also effects it

= Intellegence - it may be due to your genes but it could be to do with your environment and upbringing

= sporting ability - genes determine your ability but training also helps

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Comments

grace

Very helpful thank you

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