last min Flashcards
How do multicellular organisms exchanged substances with their environment
more difficult to exchange substances over entire body so they have transport systems to move substances from exchange surface to rest of body due to smaller surface area to volume ratio.
How are alveoli adapted for gas exchange
- moist lining for dissolving gases
- good blood supply to maintain the concentration gradients of O2 and CO2
- very thin walls
- very large surface area
What is the function white blood cells
name the 2 types
to defend against infection
- phagocytes are white blood cells which can change shape to engulf unwelcome microorganisms through phagocytosis
- Lymphocytes -produce antibodies against microoragnisms. Some may produce antitoxins to neutralise any toxins produced by microoragnisms
How are Capillaries adapted for their function
- branch off arteries
- narrow to squeeze between gaps between cells
- one cell thick cell walls so substances can diffuse
- supply food and oxygen + take away CO2
- exchange substances with cells
- large lumen
What kind of circulatory do mammals have
Double circulatory, means heart pumps blood in two circuits
-deoxygenated blood goes to lungs to get oxygen
oxiginated blood goes to heart.
-second circuit takes ooxygenated blood from heart to the body for cells then returns to heart
name an animal with a single circulatory system and how it works
Fish- deoxygenated blood from fish body goes to heart which pumps around again via gills which pick up
oxygen.
-heart only has 2 chambers
How is deoxygenated blood carried around heart
through the vena cava
- to right atrium
- through tricuspid valve, through right ventricle
- through semi lunar valve
- to lungs through pulmonary artery
How is oxygenated blood carried around heart
- through the pulmonary vein to left atrium
- through bicuspid valve,
- to left ventricle
- through semi-lunar valve
- through aorta to the body
What is the energy released by cellular respiration used for
- metabollic processes- like breakdown of proteins from amino acid
- contracting muscles-
- maintaining a steady body temperature
How does anaerobic occur
when there isnt oxygen available so glucose is only partly broken down to make lactic acid which can build up in muscles and lead to cramp
What is the formula for anaerobic respiration in plants
glucose»_space;»» ethanol + carbon dioxide
Why are photosynthetic organisms producers of biomass
Because they use energy from the sun to produce glucose
What substances are produced from glucose and their roles in the plant
energy which is used for respiration
How are leaves and their cells adapted for photosynthesis
Palisade layer has lots of chloroplasts so theyre near the top of the leaf
broad with large surface area exposed to light for photosynthesis
What are the effects of temperature, light intensity and carbon dioxide concentration on the rate of photosynthesis
Light intensity- when high intensity, rate of photosynthesis speeds
Carbon dioxide- two little slows it down as its a raw material needed
Temperature- If too hot enzyme denatures too low enzymes dont work
what is the concentration gradient
The direction osmosis and diffusion take from a high to low concentration.
active transport goes against the concentration gradient
How is a Xylem tube adapted for its function
dead cells joined together end to end with no end walls to take water from roots to stem and leaves.
strengthened with lignin
carry mineral ions too up the transpiration stream
Why is the phloem tube adapted to its function? What is translocation
Elongated living cells with small pores on end walls so food substances can diffuse through.
they transport food substances made in leaves to other parts of the plant through process of translocation
What is transpiration
caused by evaporation and diffusion
occurs usually in leaves
its the loss of water from a plant
What effects the rate of transpiration
Light intensity- brighter light the greater the rate as stomata close when its dark.
Temperature- warmer means faster transpiration as particles have more energy to evaporate and transpire
Air flow- better the air flow the more transpiration as water vapour is swept away maintaining low water concentration on surface of leaf so diffusion occurs faster
How can you measure the rate of transpiration
using a potometer and record position of air bubble. start time and measure distance moved. calculate the speed of bubble
What are the functions of these layers of leaves
Waxy cuticle- reduces water loss
upper epidermis- light is allowed through as this layer in transparent
Palisade layer- lots of chloroplasts near top so lots of light
Spongy mesophyll tissue- contains air space which increases the rate of diffusion
lower epidermis- lots of stomata which lets CO2 diffuse directly into the leaf
How do auxins cause phototropism
auxins in tips of shoots makes all side elongate so a taller shoot gets more light
How can plant growers use auxins
selective weed killers- only effect broad leaf plants- disrupts plant growth
growing cuttings from rooting powder- conatins auxins which produce shoots very quickly and can create clones
How can plant growers use Gibberellins
-controlling seed germination- make plants flower earlier or under conditions they wouldnt normally flower it stimualtes SEED GERMINATION
(can also reduce flower formation to improve fruit quality)
-proudcing seedless fruit- applied to unpollonated flowers to so fruit grows but seeds dont
-Controlling seed germination - getting seeds to germinate at time of year they would normally
How can we artificially ripen fruit with hormones
Controlling ripening of fruit- ethene is added to fruit on the way to the supermarket so when they get there the fruit will be perfect on the shelves
Advantage of using plant hormones in fruit farming?
- Get fruit at times of year where conditions wouldnt usually be right,
- produce seedless fruit
- produce clones of one plant
Disadvantages of Plant hormones in fruit farming
- Harmful to environment- fertilisers and chemicals can leak into waters
- fruit may be poor quality
- traditional farmers out of business
Where are hormones produced
In endocrine glands which release into blood stream
What is the general role of hormones in the body
They control things in organs and cells that need constant adjustment
How are hormones transported around the body
They are chemical messengers released directly into the blood
What is produced by the pituitary gland
Produces many hormones that regulate body conditions
Master gland as hormones created act on other glands directing them to release hormones which create change
What is produced by the Thyroid gland
Produces thyroxine- regulate metabolism heart rate and temperature
What is produced by the Ovaries
Oestrogen- controls mentrual cycle
What is produced by the Adrenal Gland
Adrenaline- prepare body for fight or flight
What is produced by the Testes
Testosterone- controls puberty and sperm production in males
What is produced by the Pancreas
Insulin which regulates blood glucose concentration
How does adrenaline prepare body for fight or flight
Activates processed that increase supply of oxygen and glucose to cells by binding to receptors in heart and liver to increase blood pressure glucose concentration and respiration
What is a metabolic rate
The speed chemical reactions occur in the body
What is the effect of thyroxine on metabollic rate? and a negative feedback system
When thyroxine level is too LOW, hypothalamus releases TRH which stmulate the pitauitary gland making TSH which stimulates the release of thyroxine to get level in blood back to normal
If too HIGH the release or TRH from the hypothalamus is inhibited, which reduces production of TSH so blood thyroxine level falls
What happens in the menstrual cycle
Stage 1- menstruation - Lining of uterus breaks down and is released
Stage 2- uterus lining is repaired (4-14) becomes thick layer of blood vessels
Stage 3- day 14 is ovulation egg released from ovary
Stage 4- lining (endometrium) is maintained until day 28 if no fertilised egg landed on uterus by then lining breaks down
What does Oestrogen do in the menstrual cycle
Causes uterus lining to thicken and grow
high level stimulates LH surge
What does progesterone do
released by corpus luteum after ovulation it maintains lining of uterus
when low level lining breaks down
How can hormones be used as a contraception
Oestrogen can prevent release of egg if levels are very high which is why pill must be taken everyday to inhibit production of FSH so egg development stops. `
Progesterone reduces fertility by producing thick cervical mucus which which stops sperm getting
List the 4 hormones used in the mentrual cycle, what they do and what the lead/inhibit release of, what theyre released by
FSH- released by pituitary gland
- causes egg to mature
- stimulates oestrogen production
Oestrogen- released by ovaries
- causing lining of uterus to thicken and grow
- high level stimulates LH surge
LH- by pituaitary gland
- stimulates ovulation
- makes follicle develop into corpus luteum
- corpus luteum secretes progesterone
Progesterone- by corpus luteum after ovulation
- maintains uturus lining
- inhibits release of FSH and LH
- when at low level: lining breaks down and FSH increases
How are hormones used in Clomifene to stimulate ovulation
By taking clomifene drug you are increasing your FSH and LH levels which stimulate egg maturation and ovulation
the women will then be ovulating and can have intercourse during this time to improve chance of being pregnant
How are hormones used in IVF treatment
- person takes FSH and LH before collection so more than 1 egg can be collected
- collecting eggs from ovaries and fertilising them in a lab with the male sperm
- when they have grown into embryos one of two are transferred into uterus to improve chance of pregnancy
why is maintaining a constant internal environment important
because you cells need the right conditions to function properly including rate of enzyme action.
it is dangerous for conditions to vary too much
what does the body do if blood glucose levels are too high
- Insulin is secreted by pancreas
- glucose moves from blood to liver cells
- insulin makes liver turn glucose into glygogen
what does the body do if blood glucose levels are too low
- glucagon is secreted by pancreas,
- glucagon makes liver turn glycogen into glucose
What other factors remove glucose from the blood
normal metabolism
exercise moves lots of glucose from blood as its used for respiration
excess glucose is stored as glycogen in the liver and muscles or when full as lipids and fat in tissues
What does thermoregulation mean
process of maintaining an internal temperature for enzymes to work best at
(usually around 37degrees)
where is the thermoregulatory center
in the hypothalamus in the brain-
conatins receptors which are sensitive to blood temperature in the brain.
what does your body do if youre too hot
- erector muscles relax so hairs lie flat and not trapped air and increase air flow on surface
- lots of sweat is produced in dermis
- this is released through pores on surface of skin
- when it evaporates heat is lost to environment
- blood vessels dilate through vasodilation to allow more blood flow to the surface which cools you
what does your body do if youre too cold
- erector muscles contract so hairs trap air to keep you warm
- little sweat it produced so pores close
- blood vessels constrict through vasoconstriction so less energy lost to surroundings
- shivering increases respiration which keeps you warm
why is regulating water content important
because if levels are too high then water will move into the body cells by osmosis and if theres too much then cells may burst
if too low- water will move out of cells by osmosis and cause cells to shrink
which organ helps to regulate body water content and how
3 main roles of the kidney
Kidneys-
- removes urea from blood which is produced by liver from breakdown of amino acids
- adjust ion levels in the blood
- adjust water content
they do this by filtering stuff at high pressure and reabsorbing things, waste is carried out in urine
What do nephones do
filter out certain substances
-liquid part of blood containing urea, ions, water and glucose is forced out of glomerulus and into bowmans capsule at high pressure
Explain the water content negative feedback system
more water- brain detects pituitary gland releases less ADH, less ADH means kidney reabsorbs less water
less water- brain detects, pituitary releases more ADH ADH makes kidney reabsorb more water
How does a kidney dialysis filter blood mechanically
- kidney dialysis machine filters blood for people who have kidney failure
- done regularly to keep dissolved substances at right concentrations
- dialysis fluid has the same concentration of glucose and salts as blood plasma
- the selectively permeable barrier filters out ions and waste substances but not large proteins and cells
Describe the pros and cons of a kidney transplant
+ lasts forever you dont have to keep having dialysis
- body can reject the kidney
- hard to find a donor with a tissue type to match patient
- can be attacked by antibodies (drugs are taken to reduce this)
what is a population
all organisms of one species in a habitat
what is a community
all the organisms of different species living in one habitat
How can we study the distribution of small organisms
using a quadrat
then take mean total no.oragnsims/ total number of quadrats
-to find population - multiply mean by total area of habitat
Name some factors which mean that energy is lost down the food chain
lost as heat
not all gets eaten
faeces
How do you calculate efficiency in energy levels
energy transferred to next level
/ energy transferred at previous level
How do human activities affect biodiversity
fertilisers can leach into water and cause eutrophication
- fish farming
- introducing non-indigenous species
How does fish farming reduce biodiversity
-food in nets produces large amounts of waste in water
- breeding ground for parasites
-predators attracted and get trapped in nets
-sometimes fish escape and cause problems for indigenous species
(sometimes fish are stored in tanks with low biodiversity as only one species is farmed and free from plants, predators and parasites)
How does introducing a non-indigenous species reduce biodiversity
- compete with indigenous species for food and if they out-compete can lead to native species to die out
- can bring new diseases into habitat
Name some ways we can conserve and maintain biodiverisity
- Reforestation- more variety of trees to increase biodiversity and provide food and shelter
- conservation schemes- protect habitats and species in safe areas and introducing captive breeding programmes and seed banks to distribute rare endangered plants
Name some benefits of maintaining biodiversity
name 4
- creates jobs
- protects human food supply
- minimal damage to food chains
- future medicines
- ecotourism
How does increasing consumption of meat and fish affect food security
- overfishing can cause species to die out
- feeding fish crops that could be eaten by humans
- less biomass in a food chain
How are environmental changes caused by human activity affecting food security
- burning fossil fuels releases CO2 which is a greenhouse gas which leads to global warming
- climate change reduces crop yield so less food for humans
What does food sustainability mean
meeting the needs of todays population without affecting the ability of furture populations to meet their needs
How do new pests and pathogens affect food security
cause damage to crops and livestock
-introduce diseases that can wipe out whole populations of crops can be damaged reducing yield
What is reverse Osmosis
- a method of desalination to get rid of impurities from water
- net movement of water from a lower salt concentration to a higher salt concentration over a partially permeable membrane
What is desalination
removing salts from salt water to produce potable water
-thermal desalination - salt water boiled in vessel so steam rises and leaves salts and steam condenses down pipe to form water
How can farmers increase the amount of nitrates in the soil
crop rotation
fertlisers
How can cell structures (some) only be seen with an electron microscope but not light microscope?
Due to electron microscopes having a higher resolution than light microscopes, it allows us to see greater details of internal structure of mitochondria and chloroplasts.
What is the magnification formula? (Total magnification)
Eyepiece lens magnification x objective lens magnification.
What is magnification formula including sizes?
Image size / real size
Recall the purposes of sub-cellular structures of: Vacuole
Weak solution of sugar and salts and keeps internal structure
Recall the purposes of sub-cellular structures of: Ribosomes
Translation of genetic material in synthesis of proteins
What are the common parts of a bacteria cell?
Flagellum to power along away from harmful toxins and towards nutrients and oxygen. Ribosomes, cell membrane, chromosomal DNA, PLasmid DNA for replication (small loops of extra DNA contains genes for drug resistance)
How are egg cells adapted to their function?
- Nutrients in cytoplasm feed the embryo
- Haploid nucleus
- after fertilisation, membrane changes structure to stop any more sperm getting in so embryo has right amount of DNA
How are sperm cells adapted for their function?
- Lots of mitchondria to provide energy for respiration needed to swim the distance
- Has an acrosome at front of head where enzymes are stroed to break through membrane of the egg cell
- Haploid nucleus
- Tail/flagellum to swim to egg
What are the substrate concentrations of: Lipids?
(Lipases) glycerol and fatty acids
What are the substrate concentrations of: Proteins?
(Proteases used) amino acids
What does an enzyme do?
Break down large molecules by speeding up the rate of a reaction for growth and life processes
How can we test for proteins in food?
- Biuret Test is used for proteins, first add potassium hydroxide to make it alkaline then add copper sulfate solution (blue)
- If no protein it stays blue (negative)
- If there is it turns purple (positive)
How can we test for lipids?
Emulsion test - Take sample and shake to mix with ethanol for a minute so it dissolved then pour into water
- Positive = milky emulsion (precipitate)
- Negative = clear
How can we use calorimetry to measure the energy in food?
- First get food sample which burns easily (dry)
- Weigh the food and skewer it on a needle and hold under boiling tube
- Add set volume of water to boiling tube and measure initial temperature of water
- Set fire to food sample and heat boiling tube with it until burnt out
- Measure water again and use formula:
Energy in food (J) = Mass of water x temp change x 4.2
What is an active site? (Explain the role)
Every enzyme has an active site where the substrate joins it to catalyse the reaction. The substrate has to fit into the active site and if it doesn’t fit, the reaction wont be catalysed. This is called a lock and key mechanism.
How can we investigate osmosis with potatoes?
- Get sucrose solution in ranging concentration from pure water to very concentrated sucrose
- Use a potato corer to have evenly sized potato cores
- Use mass balance to measure mass before then place into test tubes of different concentrations and leave for 40mins
- Then remove and pat dry and measure mass again (for accuracy)
- Then work out percentage change = difference mass / original x 100
describe the path of substances through the nephon
liquid part of blood forced into glomerelous then into the bowmans capsule large molecules (cells+proteins) cant get through selective reabsorption-glucose, water, ions
an indicator species for clean water
stonefly larvae, freshwater shrimp
very sensitive to dissolved oxygen
an indicator species for dirty water
blood worms, sludge worms
an indicator species for clean air
bushy lichen
blackspot fungus - on rose leaves
-dont like sulphur dioxide
an indicator species for dirty air
crusty lichen
what effects the rate of decomposition
temperature- speeds up enzyme reaction
water content- organisms need to water to carry out biological processes
oxygen availability- for aerobic respiration
How can we preserve foods
- fridge or freezer to slow down decomposers
- air tight to stop microoragnsims getting in, then sterilised at high temperature
- drying with salt removes water so microorganisms die
how are ideal conditions maintained in compost bins
- moist warm by decomposers
- mesh sides to increases oxygen availability
- insulated
