Biology B1
- Created by: felixshears
- Created on: 11-04-17 11:33
Diet
For good health you need the right amount of energy but no more
Food groups needed:
- carbohydrates - release energy
- fats - keep warm and release energy
- protien - growth, cell repair and cell replacement
- fibre - keep things moving through digestive system
- small amounts of vitamins + mixed ions - general body functioning
A person is malnourished if have unbalanced diet either way
Obesity from:
- excess carbohydrates or fats
- common in developed countries
- results in type 2 diabetes, high blood pressure + heart disease
Exercise + Metabolic Rate
Energy needed to fuel chemical reactions in the bdy to keep alive
These reactions are your metabolism + metabolic rate is speed they occur
This varies with amount of activity done + proportion of muscle to fat in body
Can be affected by inherited factors
When you exercise you need more energy so metabolic rate increases after exercise
Your activity level affects the amount of energy you need
Exercise:
- increases the amount of energy used by body + decreases amount stored by fat
- also builds muscle so it boosts metabolic rate
- you can still be physically fit but malnourished
Pathogens
Microorganisms that cause infectious diseases are pathogens
There are two pathogens: bacteria + viruses
Bacteria:
- cells 1/100th the size of your body cells
- can rapidly reproduce
- they make you ill by damaging your cells + producing toxins (poisons)
Viruses:
- not cells + 1/100th the size of bacteria
- replicate by invading your cells, making copies + bursting to release more
- this cell damge makes you feel ill
Fighting Disease
Skin, hairs + mucus prevent nasties from getting into body
Paleletes
White blood cells:
- ingest foreign cells + digest them
- produce antibodies
- produce antitoxins to counteract toxins produced by invading bacteria
Antibodies:
- every invading cell has unique molecules (antigens) on its cell
- when your white blood cells come across a foreign antigen they will start to produce protiens called antibodies to lock onto and kill invading cells
- antibodies are then produced rapidly and carried around the body to kill all other similar pathogens
- If person infected with same pathogen again the white blood cells will rapidly reproduce the the same antibodies to kill it - the person is immune
Drugs to Fight Diseases
Painkillers - relieve symptons but don't kill pathogens e.g. asprin
Antibiotics:
- kill infectious bacteria in the body
- don't kill viruses
- specific bacteria has to be treated by specific antibiotics
- over-use + over-perscription results in bacteria strains becoming resistant (e.g. MRSA)
- mutations of bacteria spread rapidly as people aren't immune
- mutations need more antibodies to be developed
Investigating antibiotics:
- hot agar jelly poured into sterilised petri dish to kill unwanted microorganisms
- inoculating loops are passed through flame to sterilise + used to transfer microorganisms to the culture medium
- paper disks soaked in antibiotics placed on them and resistant bacteria will grow + non-resistant strains will die
- petri dish lid must be taped on to stop bacteria in air getting in
- maximum temp of 25 to prevent harmful bacteria growing although would be higher in industrial conditions
Vaccination
Inject small amounts of dead or inactive microorganisms
These carry antigens which cause your white blood cells to produce antibodies to attack them
This makes the person immune as body can respond rapidly by producing antibodies
+ controls diseases e.g. MMR (Measles, mumps + rubella)
+ prevents large outbreaks of disease as population is immune
- doesn't always work
- can have negative side affects such as swelling or a fever
Semmelweis
Ignaz Semmelweis was working in Vienna General Hospital in the 1840s and saw that women were dying in huge numbers aafter childbirth from puerperal fever
He believed that doctors were spreading disease on their unwashed hands and heavily reduced deaths by telling doctors to wash hands in antiseptic solution
This is because the solution killed the bacteria although this was not known at the time and as a result his methods were droped and death rates rose again
Nervous System
Sense organs
- detect stimuli (a change in your enviroment)
- contain receptors
- eyes = light receptors (have nucleus, cyptoplasm + cell membrane)
- ears = sound + balance receptors
- nose = smell receptors sensitive to chemical stimuli
- tongue = taste receptors sensitive to chemical stimuli
- skin = sensitive to touch, pressure, pain and temperature change
CNS - the brain and spine where info from sense organs is sent
Sensory neurones - nerve cells that carry signals as electrical impulses from the reeprtors in the sense organs to the CNS
Relay neurons - nerve cells that carry signals from sensory neurones to motor neurones
Motor neurones - nerve cells that carry signals from CNS to effector muscles or glands
Effectors - muscles and glands that respond
Synapses and Reflexes
Synapses - connect two neurones and chemicals diffuse across a gap
Reflexes - help prevent injury through automatic responses e.g. bright light causes pupils to get smaller and let less light into eye
Reflex arc - passage of information in a reflex
Reflex Arc
1) A stimulus (e.g. bee sting) is detected by receptors
2) Impulses travel along the sensory neurone to the CNS
3) When an impulse reaches a synapse between the sensory neurone + a relay neurone, chemicals are released + sent along the relay neurone
4) Same thing happens + impulses sent along motor neurone
5) The impulses travel along the motor neurone to effector e.g. muscle
6) The effector then responds
Hormones and Menstrual Cycle
Hormones are chemical messengers which travel in blood to activate target cells that regulate the functions of organs + cells
Nerves - fast, act for short time + precise area but hormones - slower, act over long time + act in more general way
FSH:
- produced by pituitary gland (head)
- causes egg to mature in one of ovaries
- stimulates ovaries to produce oestrogen
Oestrogen:
- produced in ovaries
- causes pituitary glands to produce LH
- Inhibits release of FSH
LH
- produced by pituitary gland
- stimulates release of an egg at middle of menstrual cycle
Controlling Fertility
Reducing fertility:
- oral contraceptive containing oestrogen + progesterone
- previously contained more oestrogen but women suffered side effects
- + 99% effective + reduces risk of cancer
- - not 100% effective + can cause side effects such as headaches
Women can also be injected with FSH and LH to increase fertility although too many eggs could be stimulated
IVF:
- 1) mother given FSH + LH to stimulate maturation of eggs
- 2) these are collected + fertilized from sperm of the father
- 3) these are developed into embryos + one or two inserted into uterus
- + increased chance of fertility
- - women can have negative reaction to hormones and increased risk of cancer
- - increased chance of multiple births
Plant Hormones
Auxin:
- plant hormones that grow near tips of roots and shoots
- controls growth of plant in response to light, gravity + moisture
- moves produced in tips and moves backwards to stimulate cell elongation
- if tip is removed, no auxin is avaliable and may stop growing
Shoots:
- grow towards light (elongates on far side and bends)
- grow up away from gravity (elongates on far side from gravity + bends)
- auxin on one side makes it grow + elongate other way
Roots:
- grow towards gravity (down)
- grow towards moisture
- auxin makes it bend side of auxin
Plant growth hormones are extracted + used in agriculture as weed killers + rooting hormones
Homeostasis
Trying to maintain a constant internal enviroment
Things controlled:
Water content - taken in through drinking and lost through skin as sweat, trough lungs in breath and kidneys as urine
Ion content - taken in by food lost in sweat and excess ions lost via kidneys in urine so kidneys regulate ion content
Temperature - controlled by brain to maintain the best temperature for enzymes to work 37°C
Blood sugar levels - to provide cells with constant supply of energy
Testing Drugs
Scientists are continually developing new drugs which are extensively tested
The three stages are - lab (on human cells + tissues but cant test drugs that affect whole body), live animals (some people think is cruel) and human volounteers
Human:
- 1) given to healthy volounteers to ensure doesn't have side effects on healthy people. Intitially given in low dosage and then increased
- 2) if safe, given to people with the illness to find optimum dosage (most effective wit fewest side effects)
- 3) to test effectiveness - patients split into two groups + half given placebo with neither doctor or patient knowing which
Thalidomide:
- developed as sleeping pill
- found to be effective at stopping morning sickness
- hadn't been tested on pregnant women
- this resulted in abnormal limb develpment for babies
- drug testing has since become more rigorous + thalidomide used for cancer
Drugs
Change your body chemistry
These changes can cause you to become addicted + leave you with withdrawal symptons especially heroin + cocain
Different types are; medicinal (need perscription as dangerous if misused), recreational (can be legal or illegal) + performance enhancing (some banned by law + all banned by NGB)
Performance enhancing drugs:
- e.g. anabolic steroids
- for - athletes have right to make decisions
- for - athletes have different access to equipment etc so unfair anyway
- against - unfair advantage
- against - athletes not informed of dangers e.g. high blood pressure
Statins - prescribed to lower risk of heart + circulatory disease for diabetics
Recreational Drugs
Soft or hard - hard more addictive + harmful
Reasons for use - stress release, inspiration + social pressures
Cannabis:
- smoke contains chemicals which cause mental illness
- often linked with harder drug use as seen as stepping stone/gateway drug
- also damages heart + circulatory system like ecstasy and heroin
Legal drugs have bigger impact (cost on NHS and results in higher crime levels) than illegal drugs as more widely avaliable
Smoking:
- causes disease in heart, blood vessels + lungs and causes cancer
- nicotine is found in cigaretts and is addictive
Alcohol
- affects nervous system, slows body reaction, causes liver disease + brain damage
Competitions
Plants compete with each other for light, space, water + nutrients
Animals compete with each other for space, food, water + mating
This competition can lead to populations of certain creature droping
Adaptations help them survive in the conditions they live in
Animal Adaptations
Extremophiles - organsims that live in extreme enviroments e.g. high temperature
Desert animals:
- large surface areas compared to volume so can lose more heat
- lose less water through concentrated urine + little sweat
- thin layers of fat to release heat + instead kept in hump (camels)
- sandy colour to camouflage and avoid predators
Artic animals:
- small surface area to volume (round shape) to reduce heat loss
- well insulated with lots of fat (energy) + thick fur coats
- white camouflage to avoid predators
Desert Plant Adaptations + Avoiding Predators
Desert plant adaptations:
- Small surface area compared to volume to reduce water loss
- Water storage e.g. cacti store water in thick stem
- Extensive root systems to access maximum amount of water
Detering predators:
- some animals + plants have armour e.g. tortoise + cacti
- produce poisons e.g. bees + poison ivy
- warning colours e.g. wasps
Environmental Change
Caused by living factors e.g. change of:
- occurence of infectious diseases
- number of predators
- number of prey/avaliabilty of food sources
- number of competitors
Caused by non living factors e.g. change of
- average temperatures
- average rainfall
- air or water pollution
Non living factors can measure enviromental change e.g. high number of lichen indicates air is clean as damaged by sulphur dioxide
High number of invertabrate animals in water means water is clean as they are sensitive to the amount of dissolved oxygen in water
Scientists measure enviromenal change for the temp of sea, rain averages + use weather stations for predctions
Pyramids of Biomass
Every time you move up a trophic level in food chain theres less energy, less biomass and generally fewer organisms
Biomass - how much all the animals on a level weighs e.g. one fox is more than 5000 fleas
Bottom bar - producer
Second bar - primary consumer
Third bar - secondary consumer etc.
Energy Transfer + Decay
Energy transfer
- 1) energy from sun is source of energy for nearly all life on earth
- 2) green plants + algae use light energy from the sun to make food during photosynthesis which is then stored in plants
- 3) respiration supplies energy to all organisms and this is often lost to the surroundings as heat
- 4) some material in plants + animals is edible so doesn't pass to next stage and enrgy lost from wate materals
Decay process
- Energy is transferred back to start of food chain by decay
- 1) living things remove material from the enviroment for growth + other processes
- 2) plants take elements like carbon from soil + air and pass them through the food chain
- 3) these elements are returned to the enviroment in wate material or in death
- 4) these materials then decay because they are digested by microorganisms
- 5) microorgans work best in warm, moist conditions where oxygen is avaliable e.g. compost bins
- 6) these elements are then recycled + put into soil as decay process releases substances plants need to grow
- 7) in a stable community there is an ongoing cycle
Carbon Cycle
The carbon cycle shows how carbon is recycled
Order:
- 1) CO2 is removed from atmosphere by green plants + algae for photosynthesis
- 2) the carbon from CO2 is used to make carbohydrates, fats + protiens of plants + algae
- 3) some CO2 is released back into the atmosphere from respiration
- 4) when plants + algae are eaten the become fats + protiens in animals
- 5) when animals respire some of this carbon becomes CO2 + is released into atmosphere
- 6) when plants, algae + animals die some animals + microorganisms feed on their bodies
- 7) carbon is released into atmosphere as CO2 when microorganisms respire
- 8) waste from animals is taken up by soil + nutrients and then back into the cycle as plant nutrients
- 9) some plants + wood are burnt + released back into the atmosphere
Genes
The information that results in plants + animals having similar characteristics is carried by genes which are carried in gametes
Most cells have a nucleus which contains chromsones that carry genes
A gene is a short length of the chromosone + DNA is coiled up to form the arm of the chromosone
Different genes control the development of different characteristics
Variation
Genetic variation:
- all animals + plants have similar characteristics to their parents as inherited from parents after being passed on in gametes
- combining of genes from mother + father causes genetic variation
Some characteristics are only determined by genes e.g. eye colour
Enviromental variation - diffrence caused by enviroment e.g. getting a suntan
Most characteristics come from both e.g. body weight
Reproduction
Sexual reproduction - the fusion of male + female gametes. The mixture of genetic information from the parent causes the offspring to contain a mixture of their genes
Asexual reproduction - only one parent with genetically identical offspring
This is how plants and animals grow + replace cells
Bacteria + some plants use for reproduction
Animal Cloning
Embryo transplants:
- 1) sperm cells taken from prize animals
- 2) these cells used to fertilize an egg cell
- 3) the embryo created is split + the injected into other cows
Adult cell cloning:
- 1) take unfertilized egg cell and remove genetic material
- 2) complete set of chromosones from adult body cell inserted in empty cell
- 3) the egg is then stimulated + divided by electric shock
- 4) when embryo is inserted into adult female to grow into identical copy of original cell
Issues:
- reduced gene pool
- possibility of clones not being as healthy
- human cloning could come after many unsuccessful attempts e.g. children born diseased
Plant Cloning
Cuttings:
- gardeners can take cuttings from good parent plants, and then plant te to produce genetically identical copies (clones) of the parent plant
- these plants can be produced quickly and cheaply
Tissue culture:
- when a few plant cells are put into growth medium + grow into clones of parent plant
- quick
- little space needed
- all year round
Genetic Engineering
Too copy a useful gene from one organisms chromosones to the cells of another
1) a useful gene is cut from one organisms chromosones using enzymes
2) enzymes then cut out another organisms chromosones and useful gene is inserted
This method can be used to transfer genes into animals + plants at early stages of development e.g.
- GM crops - modified to be resistant to viruses, insects + herbicides and increase yield
- sheep engineered to produce substances in milk to prevent disease
- gene therapy - replacing faulty genes
Dangers of GM crops:
- may be dangerous for humans to eat
- reduce farmland biodiversity
Theories of Evolution
Darwins theory of evolution:
- all species of living things began as simple
- organisms that first developed over 3 billion years ago
Not everyone agreed with Darwin:
- challenged ideas that god created the world
- darwin didn't have enough evidence
- genes or mutations weren't discovered for another 50 years
Lamarck:
- if a characteristic used a lot by organism it would become more developed
- these aquired characteristis would be passed on
- e.g. elephants using trunk to reach food - trunk becomes longer
- we now know this isn't true
Evolution 1
All organisms are related
Classification:
- plants - make their own food by photosynthesis + fixed to the ground
- animals - don't make their own food + can move
- microorgansims - different to plants + animals
Evolutionary relationships:
- species with similar characteristics have similar genes as share common ancestors
- often look alike + live in similar habitats e.g. whales + dolphins
Ecological relationships
- how organisms interact with each other
- animals with similar characteristics are often competing with each other
Evolution 2
Natural selection:
- 1) individuals in the same species show variation because of differences in their genes
- 2) individuals who have characteristics that make them better adapted to the enviroment have a better chance of survival so are more likely to breed successfully
- 3) therefore the genes that are responsible for the useful characteristics are more likely to be passed on
Mutations:
- a change in an organisms DNA
- generally no effect but sometimes mutation can be useful
- if useful gives organism better chance of survival and reproducing
- therefore likely to be passed on to future generations by natural selection
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