B3 Flashcards
What are the 3 roles Kidneys perform?
- Removal of urea from the blood
- Adjustment of ion levels in the blood
- Adjustment of water content of the blood
Where is urea produced?
In the liver from the breakdown of excess amino acids
How do kidneys perform these roles
By filtering stuff out of the blood under high pressure and then reabsorbing the useful things. The end product is urine
What are nephrons
They are the filtration units in the kidneys
Describe ultrafiltration
- A high pressure is built up which squeezes water, urea, ions and glucose out of the blood and into the Bowman’s capsule
- The glomerulus and the Bowman’s capsule act like filters, so big molecules like proteins and blood cells are not squeezed out. They stay in the blood
What happens in reabsorption
- All the glucose is selectively reabsorbed- it’s moved out of the nephron back into the blood against the concentration gradient.
- Sufficient water is reabsorbed, according to the level of the hormone ADH. The process of maintaining the right water content in the body is called osmoregulation
Release of wastes
Urea and excess water are not reabsorbed
They continue out of the nephron, into the ureter and down to the bladder as urine. Urine is released through the urethra.
How is water content regulated in the kidneys?
By a negative feedback system
The amount of water reabsorbed in the kidney nephron is controlled by Anti diuretic hormone
Describe the negative feedback system that regulates water content
The brain monitors the water content of the blood and instructs the pituitary gland to release ADH into the blood according to how much is needed
Negative feedback
Where changes in the environment trigger a response that counteracts the changes. This means that the internal environment tends to stay around a norm, the level at which the cells work best.
If the water content gets too high or low, negative feedback brings it back to normal
When there is too much water…
Pituitary gland releases less ADH
When there is too little water…
Pituitary gland releases more ADH
More ADH makes
The Kidney absorb more water
What is dialysis
Patients who have kidney failure can’t filter their blood properly so a dialysis machine does it for them
Dialysis has to be done regularly
Dialysis fluid has the same concentration of salts and glucose as blood plasma
Cell metabolism produces what?
Waste products like urea and carbon dioxide
How are egg cells specialised for reproduction
- contain nutrients in the cytoplasm to feed the embryo
- Straight after fertilisation the membrane changes to stop any more sperm getting in
- the egg contains a haploid nucleus
What is the main function of the egg
To carry the female DNA and to nourish the developing embryo in the early stages
What is the function of the sperm cell
To transport the males DNA to the female egg
How is the sperm cell specialised for reproduction
- small and have long tails to swim
- have lots of mitochondria in their middle section to provide energy to swim the distance
- acrosome at the front where enzymes they need to digest through egg membrane are stored
- contains haploid nucleus
Menstrual cycle
Day 1- uterus lining breaks down
Day 4 -14 - lining of the uterus builds up again
Day 14- egg is released from ovary
Day 28- if no egg is fertilised the lining breaks down again
FSH
Causes a follicle to mature in one of the ovaries
Stimulates oestrogen
Oestrogen
Causes the lining of the uterus to thicken and grow
High level stimulates an LH surge
LH
Stimulates ovulation at day 14, the follicle ruptures and the egg is released
Stimulates the remains of the follicle to develop into a corpus luteum which secrets progesterone
Progesterone
Maintains the lining of the uterus
Inhibits FSH and LH
When level falls, and there’s a low oestrogen level the uterus lining breaks down
A low progesterone level allows FSH to increase
Placenta
Supplies the baby with oxygen, glucose and nutrients
Removes waste products
What was pasteurs experiment
Pasteur heated broth in two flasks, left them open
One had a curved neck so that the bacteria settled in the loop and couldn’t get through
One stayed fresh but the other didn’t, showing it was the microbes not the air causing it to go off
How do B- lymphocytes respond to invading microorganisms
When the B-Lymphocytes come across a foreign antigen, they produce proteins called antibodies which bind to and kill the new invading cells
The antibodies produced are specific to that antigen
Antibodies are produced rapidly and flow all around the body to kill all similar bacteria or viruses
Monoclonal antibodies
Hybridoma cells divide quickly to produce lots of identical antibodies called monoclonal antibodies
You can make ones that bind to any specific antigen- only targets one cell
How are monoclonal antibodies used in pregnancy tests
The first window has antibodies with blue beads attached, the test strip has antibodies that are stuck down
If you are pregnant then the antibodies bind to the hormone and are moved up the stick
The beads with the hormone bind to the antibodies on the strip turning that section blue
How are monoclonal antibodies used to detect cancer
Cancer cells have special cells called Tumour markers
The antibodies are labelled with a radioactive element, given through a drip into the blood
They bind to the tumour markers and are detected with a special camera
How are antibodies used to kill cancer cells
Drug kills the cancer cells but not any other cells near it
Less side effects
How can antibodies be used to find blood clots
When blood clots, proteins in the blood join together to form a solid mesh
Monoclonal antibodies bind to these proteins with a radioactive element
Germination of Arctic plants
When the days are long so they know it’s summer
Long day plants
Only flower when the day is at least a certain length
Eg spinach
Short day plants
Only flower when the days are less than a certain length so they flower in early spring or autumn
Eg primroses
To ensure they only flower when the right insects are about
Sleep patterns
When it gets dark your body produces more melatonin which makes you sleepy
Having regular sleep patterns is good for your health and ensures you feel awake at the right time
Urine production
At night ADH levels increase which reduces urine production
Stomata opening
During the day photosynthesis occurs, the stomata open to let in CO2 and O2 in and out
At night photosynthesis stops so stomata can close to reduce water loss
Flower opening
Flowers only need to be open when the creatures that pollinate them are active
Tobacco flowers-pollinated by moths only open at night
Classical conditioning
When an animal learns passively to associate a neutral stimulus with an important one, the response is automatic and reinforced with repetition
Eg Ivan Pavlov- classical conditioning in dogs
Operant conditioning
Where an animal learns actively to associate an action with a reward or punishment
Eg Burrhus skinner- Operant behaviour in pigeons and rats
Animal training using operant conditioning
Training guide dogs to stop at a roadside and wait for a command
Training police sniffer dogs to retrieve drugs
Training police horses to only respond to commands from their riders
When is classical conditioning used in combination with operant conditioning
When a reward can’t be given at the exact time the act is carried out
For example in Dolphins, the fish cannot be given at the exact time the dolphin does the jump so a whistle is blown instead.
The whistle shows the dolphin it will get the fish
Why do plants release chemicals
Attract pollinators
Attract insect predators
Warn other plants
How do plants attract pollinators
Lots of flowers release scented chemicals which attract pollinators who are looking for nectar. While they are there some pollen gets stuck to them
How do plants attract insect predators
Some plants release chemicals into the air when a pest is eating them
These attract a predator insect which feeds on the pest but not the plant
How do plants warn other plants
Some plants have leaves that can release chemicals into the air if they are being eaten
When another leaf detects them it makes chemicals that make the leaf harder to digest
Another plant nearby detects the signal and they prepare themselves in the same way
Why have plants and their pollinators co evolved
It’s an advantage for both as the insect has less competition and the insect is more likely to visit other flowers of that type
Eg orchids and moths- deep nectar store
Why do plants and their pests co evolve
Some plants produce nasty chemicals so most insects can’t eat them
Some insects can eat poisonous plants so less competition
Eg caterpillars of the cinnabar moth eat ragwort
How did settlers on the coast of the near East and Asia change
Started to eat shellfish and seafood
New stone tools to get them out of their shells
How did settlers in Australia change
Rainforest so eating fruit that grew in trees
New tools to reach it- long sticks
How did settlers in Europe change
Changed their diet Larger animals so new methods of hunting so they could hunt in groups New tools like knives and saws Colder climate so more shelters Animal skins to make warm clothes
How humans adjusted to the ice age
More shelters Fire Warm clothing made of skins and fur Hunting increased Make and use more tools Cooperation and communication increased Language developed
Mycoprotein
Meat substitutes for vegetarians
Fungus fusarium is grown in fermenters using glucose syrup as food
Respires aerobically so needs oxygen
More protein, fibre, less fat than meat
Producing yoghurt
Equipment sterilised
Milks pasteurised then cooled
Lactobacillus bacteria is added and the mixture is incubated in a fermenter
Bacteria ferment the lactose sugar to form lactic acid
This causes the milk to clot and solidify into yoghurt
Advantages of using microorganisms for food production
Grow quickly Easy to look after Not affected by climate Use waste products from agriculture and industry as food Cheaper
What enzymes can be used in food production
Chymosin
Invertase
How is chymosin used in food production
Cheese is made using rennet
Rennet is obtained from calfs stomach lining containing the enzyme chymosin which clots the milk
Genes for chymosin were isolated from the stomach cells and put into yeast cells
How is invertase used in food production
Used to manufacture sweets and other foods
Converts sucrose into glucose and fructose which are sweeter so less sugar is needed for the same sweetness
Cheaper, lower calorie
Naturally produced by the yeast saccharomyces cerevisiae
Non biological washing powders
Contain chemicals which break up the stains
Biological washing powders
Contain the same chemicals as non-biological but with enzymes which break down the starch proteins and fats
More effective at low temperatures
Work best at pH 7
Immobilised enzymes
Enzymes attached to an insoluble material or encapsulated in alginate beads so they don’t dissolve into the mixture
Can be easily separated and re used
Immobilised enzymes in lactose free milk
Mix sodium alginate and lactose together in a syringe
Add the mixture one drop at a time into calcium chloride
They should form beads
Put nylon gauze in a syringe and add the beads into it
Slowly add the milk to the syringe, collect the treated milk in a beaker
Test for glucose
Why make lactose free milk
The sugar lactose is naturally found in milk, it’s broken down by lactase to form glucose and galactose which are absorbed into the blood
Some people lack lactase so the lactose isn’t broken down and causes abdominal pain, wind and diarrhoea
Pectinase
Used in fruit juice extraction. It breaks down pectin (a part of the cell wall) causing the cell to release its juice
How do u use pectinase in the lab
- Chop up an apple into small chunks and divide it into two beakers
- Add pectinase solution to one of the beakers, and add the same volume of water to the other, then stir
- Incubate the beakers at 40*C for 15 mins
4 filter out the contents and record the volume of juice you get from each
How do restriction enzymes work
They recognise the specific sequence of DNA and cut the DNA at these points
The cut leave some of the DNA strands with unpaired bases- called a sticky end
Transgenic
When something contains a gene transferred from another species
How is human insulin made
- Plasmid removed from the bacterium
- Insulin gene is cut out of a human chromosome using a restriction enzyme
- The plasmid is cut open using the same restriction enzyme leaving the same sticky ends
- The plasmid and human gene are mixed together and ligase is added to join the sticky ends and produce recombinant DNA
- Inserted into bacteria, the bacteria is grown in a fermenter
What’s agrobacterium tumefaciens?
Pathogen that invades plant cells and inserts its genes into the plants DNA
Used as a vector
How are herbicide resistant plants made
- Get a plant that already has resistance and cut out the gene from one of the cells
- Remove the circular loop of DNA from the bacterium and insert the gene
- Allow bacteria to ‘infect’ the cells of the target plant, they will insert their genes into the plant DNA
- Cells are grown on a medium containing herbicide- ones that grow must contain the herbicide resistant gene
How to increase food production
Reducing pest numbers
Selective breeding programs
GM plants
Reducing pest numbers
This can be done using
- Insecticides
- GM crops to kill pests
- Crop rotation to stop pests building up
- Biological control- pest predators
Selective breeding programs
Parent plant with the best characteristics are selected and bred with each other
The best of the offspring are selected and bred
Repeated over several generations to develop the desired traits
Biogas
- Microorganisms decompose waste material to produce biogas
- 70% Methane and 30% carbon dioxide
- Burned to power a turbine
- Fuel for cars and buses
Biodiesel
- An alternative fuel similar to diesel which can be used in vehicles
- Doesn’t take much alteration
- Made from vegetable oils, animal fats or waste cooking oil
Ethanol
- Can be burnt as a fuel
- Cleaner than petrol or diesel producing fewer pollutants
- Produced by using yeast to ferment glucose
- Cars can be adapted to run on a mixture of ethanol and petrol known as gasohol
Advantages and disadvantages to biofuels
- Sustainable, replaced quickly
- Carbon neutral
- Fairly clean- less particulates
- Not much sulphur dioxide produced
- Takes up land
- Power stations and vehicles need to be adapted which takes time and money
How can u make crops resistant to pests
- Bacillus Thuringiensis produces a toxin that kills many of the insect larvae that are harmful
- Gene for the Bt toxin is inserted into crops which produce the toxin in their stems and leaves
- Harmless to humans, and animals but long term effects of exposure are unknown
- There’s a danger they’ll develop resistance
How to farmers reduce pest resistance to the Bt toxin
By using other insecticides too
How can biotechnology help provide food to developing countries
- GM pest resistant- crop yields
- GM grow in drought conditions- crop yields
- GM deficiency diseases
- Some people say it’s because they can’t afford food not because there is none
- Fears countries may become dependent on companies that sell GM seeds
- Doesn’t tackle the problem of poor soil
Aspirin
- Treat pain and lower fever
- Developed from a chemical found in the leaves and bark of the willow tree
Taxol
- Anti-cancer drug
- Comes from the bark of the Pacific Yew tree
- Discovered when scientists were screening loads of plants looking for potential treatments
Quinine
- South American cinchona tree
- For years it was the main treatment against malaria
How do pests reduce crop yields
- Fruit flies feed on fruit and ruin entire crops
- Weeds that grow near compete for nutrients in the soil, crop yield is lower
- If a plant is infected with a pathogen, some of its energy is taken by the pathogen or try and replace dead parts
- Add to the cost of producing food- money for pesticides
- Low crop yield mean high prices for customers
Pros of immunisation
- Epidemics can be prevented if a large percentage of the population are immunised, even the people that aren’t immunised are less likely to catch it
- Some diseases have been virtually wiped out by immunisation
Immunisation cons
- Doesn’t always work
- Can have a bad reaction to the vaccine, but these are rare
Hormones for fertility
Some women have low levels of FSH which means no eggs are released and the women can’t get pregnant, so it can be injected
- Helps people the get pregnant when they couldn’t
- Doesn’t always work
- Too many eggs stimulated resulting in twins etc.
IVF
In vitro fertilisation involves collecting the eggs and fertilising them in the lab using the sperm,
when the Embryos are a ball of cells one or two are transferred to the uterus
FSH and LH are given before collection to stimulate egg production
Pros and cons of IVF
-Gives infertile couple a child
- Some women have a strong reaction to the hormones
- Reports of an increased risk of cancer
- Multiple births which can be risky for the mother and baby (higher chance of miscarriage)
IVF with donated eggs pros and cons
- Allows woman who can’t produce eggs to have a baby
- Can prevent risk of genetic disorder
-Emotionally difficult - different genetic mother
Surrogate mother pros and cons
- Allows couple to have a child if she can’t become pregnant or it’s risky for her to give birth
- Surrogate mother has the right to keep the child as she is legally the mother until it is adopted by the intended couple
Ardi
- Ardipithicus ramidus
- Ethiopia
- 4.4 million years
- Climbed trees- structure of feet
- Long arms and short legs- More ape than human
- Brain size same as chimpanzee
- Walked upright
Lucy
- Australopithecus afarensis
- Ethiopia
- 3.2 million years old
- Arched feet more adapted to walking
- Moderate size of arms and legs
- Brain larger than Ardi’s but similar to chimps
- Walked more efficiently than ardi
Turkana Boy
- Homo erectus
- 1.6 million years
- Short arms and long legs much more human
- Brain size is much larger- similar to humans
- Even better adapted to walking upright
Mitochondrial DNA
- Inherited from the mother
- High mutation rate
- Lots of copies of Mitochondrial DNA
- Less likely to degrade over time
Using mitochondrial DNA as evidence for human evolution
- The more different two samples are the further back they shared a common ancestor
- Everyone on the planet has similar mitochondrial DNA
- Everyone is descended from one woman who lived in Africa 200,000 years ago
How to date a rock (not THE rock lol good luck with that)
- Stratigraphy
- Dating any fossils found with the tools
- Using carbon-14 dating to date any materials made from carbon
Behaviour
An organisms response to changes in its environment
Innate behaviour
- Inherited behaviour, reflexes
- Protect us from dangerous stimuli
Examples of reflexes
- Earthworms show negative phototaxis- move away from light
- Sea anemones wave their tentacles when stimulated by chemicals emitted by their prey
Learned behaviour
Let’s animals respond to changing conditions
Habituation
If you keep giving an animal a stimulus that isn’t beneficial or harmful they learn not to respond
By ignoring non-threatening and non rewarding stimuli, animals can use their energy more effectively
Imprinting
- Combination of learned and innate
- The animal learns to recognise its parents and instinctively follows them.
- Occurs in species that can move soon after they’re born
- Has an instinct to follow the first thing it sees but has to learn what this is
Why do animals communicate
- Help keep the group together
- Warn others about predators
- Communication of mood can avoid unnecessary fighting
- Baby animals can communicate needs to parents
- Allows predators in a group to coordinate attack
How can animals communicate
- Sound
- Chemicals
- Visual signs
How do animals use sound to communicate
- Humans through language
- Wales and dolphins through infrasound
- Birds calls declare territory, attract mates of warn others from predators
How can animals use chemicals to communicate
Chemicals called pheromones can be released to tell others where it is or has been
- Many use chemical scents to mark territory
- Some are for sexual attractants- in some moths the male can detect the females pheromone from several kilometres
Examples of visual signals
- Honey bee waggle dance when they return to the hive to tell the others they’ve found food
- Body language and posture
- Use behaviour to intimidate others and avoid an actual fight
- To admit defeat or attract a mate
- Facial expressions
Ethologyst
Study animal behaviour
