bio paper 2

structure of the urinary system

kidneys - ureters transport urine from the kidneys to the bladder - the urethra takes the urine from the bladder to the outside - sphincter muscles control whether urine can exit.

structure of the nephron

glomerelus - bowmans capsule, proximal convoluted tububle, loop of henle, distal convoluted tububle, collecting duct

what is ultrafiltration

the blood pressure in glomerulus is very high - forces materials into the bowmans capsule - large materaisl like red blood cells, white blood cells and proteins stay in blood as they are large molecules

what is the glomerular filtrate

glucose, water, salts and urea - no proteins or blood cells

why does selective reabsorption occur in the proximal convoluted tubule

important components of the blood - glucose - is filtered out initially by diffusion then active transport

how does the kidneys carry out excretion

1.)Blood is brought to the kidney in the renal artery which branches off the aorta.

2.)The kidney regulates the water and salt content and removes urea.

3.)The filtered excess water, salts and urea form urine.

4.)The urine is transported to the bladder along the ureters.

5.)The bladder stores the urine until it is convenient to expel it from the body through the urethra.

6.)The purified blood returns to the circulation through the renal vein and to the heart through the vena cava.

how does the kidney carry out osmoregulation

water content is controlled in the collecting duct - low water content is detected by teh hypothalamus so more ADH is produced - collecting duct becomes more permeable to water so absorbs more water back into the blood - more concentrated urine is produced

what is the source of ADH

pituitary gland

what is the source, role and effect of FSH

Source - Pituitary gland

Role - Female sex hormone

Effect - Causes an egg to mature in an ovary. Stimulates the ovaries to produce oestrogen.

source, role and effect of LH

source: pituitary gland

Role: releases mature egg cells for fertilisation

Effect: stimulates production of progesterone

what does urine contain

water, urea and ions

describe a DNA molecule

two strands coiled to form a double helix, the strands being linked by a series of paired bases: adenine (A) with thymine (T), and cytosine (C) with guanine (G)

what does a nucleotide contain

sugar, phosphate, nitrogen base

platelets role in blood clotting

- blood vessel is broken and blood oozes through cut- platelets in blood release chemicals.- clotting factors convert fibrinogen to fibrin.- fibrin forms mesh across wound, trapping red blood cells and forming clot.

what does blood clotting do

prevents excess bleeding and pathogens from enterring

what do memory cells result in

sooner, faster reaction time to pathogen and greater quality of lymphocytes produced

how does a vaccination result in memory cells

- the lymphocytes are able to create antibodies to fight the infection and once that infection has gone one memory cell is made which is long lived and is able to recognize the pathogen and the needed antibodies.

advantages of using stem cells

they are undifferentiated and so can differentiate into many different types of cells

They can cure some diseases e.g bone marrow stem cells can turn into red blood cells and replace faulty ones

They can also turn into insulin-producing cells for people with diabetes

They can also turn into nerve cells for people who are paralysed by spinal injuries

disadvantages of using stem cells

unethical - People say human embryos shouldn't be used for experiments since each one is a potential life

People think scientists should research other ways of finding stem cells instead of human embryos.

what is rna

a single strand of DNA that contains uracil instead of thymine

transcription

- RNA polymerase binds to a region of non-coding DNA in front of a gene- the 2 DNA strands unzip- it uses the coding DNA in the gene as a template to make mRNA- the mRNA moves out and joins with a ribosome.

translation

- amino acids are brought to the ribosome by tRNA.- the order of AA replicate the codons.- the amino acids are joined together creating a polypeptide/protein.

mRNA role

the copy of DNA that can be translated into a protein as DNA can't leave the nucleus.

what are anticodons

A set of three nucleotides bases found on the tRNA. It is complementary to the codons on the mRNA. they allow the amino acids to go in the right order.

what are codons

a sequence of three nucleotides that together form a unit of genetic code in a DNA or RNA molecule.

what effect do most mutations have on the phenotype

most have no effect, small effect - rarely significant

how can mutations be increased

exposure to ionising radiation - gamma/ultraviolet rays - some chemical mutagens - chemicals in tobacco

what is codominance

when both alleles contribute to the phenotype

what is the term biodiversity

the variety of plant and animal life in the world or in a particular habitat

what is the role of diffusion in gas exchange

- In the circulatory system oxygen enters the blood and carbon dioxide leaves the blood via gas exchange.

- Gases diffuse across the walls of alveoli to an area of lower density than they are in: oxygen moves into the blood as there is a low concentration of oxygen in the blood; carbon dioxide moves into the lungs as it is an area of lower concentration.

how is the leaf adapted for gas exchange

- Large surface area to absorb light and carbon dioxide

- Thin and flat so short diffusion distance for carbon dioxide and oxygen

- Lots of chloroplasts containing chlorophyll for photosynthesis

- spongy mesophyll have air pockets to gas can diffuse + near bottom for absorption

stomatas role in gas exchange

control gas exchange by opening and closing pores

when does respiration happen

during day and night - cells need energy to survive

what does the net exchange of carbon dioide and oxyen depend on

intensity of light

how is water absorbed by root hair cells

via osmosis - higher water concentration in the soil to lower conc in the vacuole through selectively permeable membrane

large surface area

what is transpiration

evaporation of water from the surface of the plant

humidity affect on transpiration

shallowed conc gradient - diffusion out of leaf slower

high temp affect

evaporation increases, conc gradient increases, diffusion increases

high wind speed

removal of diffused particles, maintains conc gradient

low light intensity

low photosynthesis - no need for gas exchange - stomata closed - no transpirtation

role of nitrogen fixing bacteria

they have enzymes which combine nitrogen and ydrogen gases from soil air - given to plant host - ASSIMILATION

decomposers role

they digest DNA, AA nad proteins in the plant in decomposition - releasing ammonium into the soil

nitrifying bacteria role

convert ammonium ions in soil to nitrites and nitrites to nitrates - assimilation then occurs.

denitrifying bacteria role

absorb nitrates and convert them back into nitrogen and hydrogen gas - denitrification

what is micropropogation

impact of changing DNA

affect the phenotype by altering sequence of amino acids in a protein

how can cloned transgenic animals be used to produce human proteins

stages of cloning an animal

- donor cell taken from udder

- diploid nucleus taken from donor cell into egg

- egg cell taken from female adult

- nucleus from the egg is removed creating an enucleated cell

- the egg cell and nucleus from two different sheep are put together

- cell begins to divide normally

- embryo is placed in uterus of foster mother

- embryo develops into normally into a lamb

how havw cloned animals able to produce human proteins

transferring human genes into cells of animals they acan produce human proteins in their milk

they can be then cloned to pass on these characteristics

describe micropropagation

- plant with desired characteristics is cosen to be cloned

- explants are taken from the tups of the stems and side of teh shoots of the plant

- explants are sterilised to kill any microorganisms

-explants grow in vitro - placed in a petri dis containing nutrient medium - containing growth hormones

- cells in explants devide and grow to small plants

- small plants placed into planted soil into glasshouses

fish farming methods

- kept in small cages to prevent energy loss from swimming

- protects them from interspecific predation - predation by other species

- food pellets carefully controlled to maximise energy - quicker and bigger fish will grow

- separates ages to prevent intraspecific predation

- biological control used to prevent diseases from things such as sea lice.

- selective breeding