b2 - scaling up (copy)

dosnt include labelling of the heart for that visit :https://www.geoguessr.com/vgp/3805

whats diffusion

the movement of particles from a higher to a lower concentration

how does increasing the temperature affect diffusion

the rate of diffusion increases as particles have more kinetic energy and move faster

how does the surface area of the membrane affect diffusion

as surface area increases so does the rate of diffusion as there is more space for the particles to move through

whats a concentration gradient

occurs when the concentration of particles is higher in one area than another- like a gradient/slope of concentration

what does it mean when somethings against a concentration gradient

moving from an area of low concentration to an area of high concentration ( like going uphill)

what does it mean when somethings going down a concentration gradient

moving from and area of high concentration to an area of low concentration (like going downhill)

how does the concentration gradient affect the rate of diffusion

the bigger the concentration gradient, the faster the rate of diffusion

in what substances does diffusion happen

in liquids and gases

what are the 3 ways substances can move in and out of cells

1. diffusion

2. active transport

3. osmosis

whats active transport

movement of particles across a membrane from a lower to a higher concentration - against a concentration gradient using ATP released during respiration

what are the differences between active transport and diffusion

• active transport requires energy from respiration as it is working againt the gradient , diffusion dosn’t

• active transport is against the concentration gradient whereas diffusion is down a concentration gradient

whats an example of active transport in the digestive system

• substances such as glucose from your food have to move from your gut to your bloodstream

• sometimes there can be a lower concentration of sugar molecules in the gut than the blood meaning diffusion cant take place

• active transport is required to move the sugar to the blood against its concentration gradient

whats a partially permeable membrane

a membrane with very small holes in it to allow small molecules through but larger molecules cant pass through

whats osmosis

the movement of water molecules across a partially permanent membrane from an area of higher water concentration to an area of lower water concentration

what kind of molecule can diffuse through cell membranes

• small molecules e.g. glucose, amino acids water and oxygen

• big molecules e.g. starch and proteins cant fit through the membrane

whats water potential

the potential (likelihood) of water molecules to diffuse out or into a solution

what does it mean of you have high water potential

you have a high concentration of water molecules

true or false - water can pass both ways across a membrane during osmosis

true - water molecules move about randomly all the time

what are turgid cells

cells full of water by the process of osmosis

explain how plant cells become turgid

• watering plant increases water potential of soil around it

• plant cells draw in water through osmosis to become turgid

what happens in a plant cell if there’s no water in the soil

• the plant starts to wilt

• the cells become flaccid - start to loose water

whats mitosis

when a cell reproduces itself by splitting to form two identical offspring

what are the 5 main stages in the cell cycle of mitosis

1. Cellular growth - the cell gets larger and produces more sub-cellular structures, such as mitochondria and ribosomes. 

2. DNA replication - chromosomes duplicate, so that each consists of 2 arms (copies).

3. More cell growth.

4. Mitosis - the DNA divides into two.

5. Cytokinesis - the cell divides into two.

what happens during mitosis

• the cell has 2 copies of itself spread out in long strings

• the dna forms x shapes chromosomes (each arm is the exact copy of the other)

• the chromosomes line up at the centre of the cell and cell fibres pull them apart to opposite sides of the cell

what happens during the division (cytokines)

• membranes form around each of the 2 new sets of chromosomes - they become the nuclei

• cytoplasm divides

• produced 2 daughter cells genetically identical to each other + the parent cell

how many chromosomes do humans have

46 (23 pairs)

what is cell differentiation

process by which a cell becomes specialised for its particular function

why do cells become specialised

perform specific functions / allow organisms to work efficiently

how is a sperm cell specialised

• long tails ans stream lined heads to help them swim.

• They also have lots of mitochondria to provide them with lots of energy.

• has digestive enzymes in its head to allow it to break through the wall of the egg

how is a structure of a red blood cell specialised

• biconcave shape for large surface area to absorb+ release oxygen

• dont have a nucleus so can carry more oxygen

• small and flexible so can pass easily through capillaries

how are nerve cells specialised to carry electrical impulses

• have a long axon to transport the electrical impulses long distances

• have branches connections at each end to join to other nerve cells, allowing them to pass messages around the body.

• They have a fatty (myelin) sheath that surrounds them. The fatty sheath increases the speed at which the message can travel.

how are root hair cells specialised to take up water and minerals

• Root hair cells are specialised to take up water (osmosis) and mineral ions (active transport) from the soil as they are found in the tips of rooys

• have a large surface area due to root hairs for faster diffusion

• Contain list of mitochondria which release energy from glucose during respiration to provide the energy needed for active transport

what are stem cells

undifferentiated cells which can develop into lost of different types of cells

what are the 2 key features of stem cells

1. they can divide by mitosis to form more cells

2. they can differentiate into specialised cells

where are stem cells present

• embryos

• adult animals

• meristems in plants

what are embryonic stem cells

found in human embryos and have potential to turn into any type of cell

where are adult stem cells found

bone marrow

whats the difference between adult and embryonic stem cells

• embryonic can differentiate into any type of cell

• adult stem cells can only differentiate into a narrow range of specilaised cells (e.g. afult stem cells in bone marrow can only differentiate into speocfic types of bloos cells)

what are the uses of embryonic stem cells

• can grow into any type of cell found in the body

• all tissues and organs can be potentially regrown

• however transplanted tissues and organs may be rejected by the patients immune system

• difficult to obtain and store embryonic stem cells

what are the uses of adult stem cells

• Adult stem cells are found only in specific areas of the body and can only develop into a limited number of cell types e.g. bone marrow, breasts and intestines.

• however as from the same body, would not reject their own cells

why are stem cells so important

because they have the potential to develop into different types of cells in the body which can be used for development, growth and repair

what are meristems

only plant cells which divide by mitosis found in plant tissues that are continually growing - the roots and shoots.

whats the disadvantage of specialised cells

once theyre specialised, theyre onlt adapted to carry out 1 job

what are the 3 main factors affecting the movement of substances

1. surface to volume ratio

2. temperature

3. concentration gradient

how does the surface to volume ratio affect the movement of substances

rate of diffusion,osmosis or active transport is higher in cells with larger surface area to volume ratio

how does the concentration gradient affect the movement of substances

• substances move in and out of the cell faster if theres a big difference in concentration between the inside and outside of the cell

• of there are more particles on one side, there are more there to move across

why is diffusion quicker in a single celled organism

• substances can diffuse straight into and out across the membrane as they only have to travel a short distance

• they have a relativity large surface area to volume ratio which means they are able to exchange enough substance across the cell membrane to supply the volume of the cell

why is it more difficult to diffuse substances in multicellular organisms

• its too slow as some cells are deep inside the organism meaning its a long way from them to the outer environment

• larger organism have a low surface area to volume ratio meaning you cant supply enough substances through the small outer surface for the large volume organism

how do multicellular organisms exchnange substances

they cant do it through their outer membrane so have to use specialised exchange surfaces

what 4 substances are transported within organisms

1. oxygen in for respiration

2. co2 is transported out from respiration

3. dissolved food molecules from digestion

4. urea and waste products

whats a transport system

an efficient system to transport substances from organs to the cells that use them.

what are some examples of transport systems in animals

circulatory system and the digestive system

what are examples of transport systems in plants

xylem and phloem

how are exchange surfaces in specialised exchange organs adapted to maximise effectiveness

• walls are thin so only have short distance to travel

• large surface exchange area so lots of molecules can diffuse across at the same time

• in animals have good blood supply to help maintain a concentration gradient

• permeable membranes for substances which they need to exchange - allow to diffuse across

how are the lungs adapted for gas exchange

• contain alveoli whihc have to exchange oxygen and carbon dioxide

• large surface area

• thin walls

• a good blood supply

• a moist lining for dissolving gases

how are villi adapted to exchange nutrients

• small intestine contains villi dissolve food molecules from the digestive system are absorbed quicker into the blood

• they have a single layer of surface cells which increase surface area - dissolved food molecules absorbed more wuickly inyo blood

• have a very good blood supply to assist quick absorption

explain how the structure of a leaf allows gases to diffuse in and out of cells

• leaves are broad so have a large surface area for diffusion

• they’re thin which means gases only have to travel a short distance

• air spaces inside the leaf lets gases move easily between the cells and increases the surface area increasing the chance of oxygen to get into cells

• underneath of leaf covered in stomata through which carbon dioxide diffuses into leaf and water vapour diffuses out

describe the transport of water and mineral ions into a root hair cell

• water is drawn into root hair cell by osmosis as there is usually a higher concentration of water in the soil than inside the plant

• mineral ions move into the root hair cell by active transport since the concentration of minerals is usually higher in the root hair cells than the soil (otherwise minerals would diffuse out of the root hair cells)

how are root hair cells adapted to take in water and mineral ions

• cells on plant roots grow into long hairs which stick out into soil

• each branch of root covered in these microscopic hairs

• gives plant big surface area for absorbing water and mineral ions from soil

how do you find the surface area of an object

the sum of all the areas of the faces

how do you find the surface area to volume ratio

you find the surface area and divide it by the volume

whats the double circulatory system

Two circuits carrying the blood from the heart to the lungs and back and from the heart to around the body and back

what are the advantages to mammals having a double circulatory system

• returning blood to the heart after its picked up oxygen at the lungs means it can be pumped out around the body at a higher pressure

• this increases rate of blood flow at the tissues (blood can be pumped around body faster) so more oxygen is delivered to the cells

• important for mammals ad take up a lot of oxygen maintaining body temp

describe the route that of blood in a double circulatory system

• blood flows into right atrium from vena cava

• atria contracts pushing blood into the right ventricle

• the ventricle contract forcing blood into pulmonary artery and out the heart

• blood then flows into lungs through arteries and returns through the pulmonary vein

• the oxygenated blood will then flow into the left atrium

• atria contracts pushing blood into left ventricle

• ventricle contract pushing blood into the aorta and out the heart

• blood goes around body and returns through the vena cava again

what are the 3cdifferent types of blood vessels found in the circulatory system

1. arteries

2. capillaries

3. veins

what do arteries do

carry blood away from heart

how are arteries adapted to their function

• heart pumps blood out at high pressure so the artery walls are strong and elastic

• walls are thick compared to size of lumen

• contain thick layers of muscle to make them strong and elastic fibres to make them stretch and spring back

what do cappilaries do

are involved with the exchange of materials at the tissues

how are capillaries adapted to their function

• carry the blood really close to every cell in the body so can exchange substances with them

• permeable walls so substances can diffuse in and out

• supply food and oxygen and take away waste (co2)

• walls one cell thick - increases rate of diffusion

what do veins do

carry blood to heart

how are veins adapted to their function

• blood is at low pressure so walls dont need to be as thick

• bigger lumen than arteries to help blood flow

• valves to keep blood flowing in right direction

if an animal has a small surface area to volume ratio what does this mean

their volume is large compared to their surface area

why is the left ventricular wall thicker than the right ventricular wall

has to pump blood further around the body compared to the right side

what side of the heart pumps deoxygenated blood to the lungs

the right side of the heart

whats the functions of valves in the heart

valves stop the blood from flowing backwards

how is cardiac muscle adapted to its function

cardiac muscle contains lots of mitochondria to provide the cells with ATP so the cardiac muscle can contract

what does blood consist of

plasma, platlets, red blood cells, white blood cells

what do red blood cells do

transport oxygen from the lungs to all the cells in the body

what is plasma

liquid that carries everything in blood

what are 2 waste products carried away in plasma

1. carbon dioxide ( carried from body cells to the lungs to be breathed out)

2. urea ( carried from liver to the kidneys where its removed in urine)

how is plasma adapted to its function

Plasma is clear and watery. This makes it suitable to transport molecules as many of them are soluble in water.

what is the function of red blood cells

to transport oxygen from the lungs to all the cells in the body

how are red blood cells adapted to their function

• small and biconcave disc shape to give large surface area to volume ratio for absorbing + releasing oxygen

• dont have a nucleus - frees up space for more haemoglobin so they can carry more oxygen

• small and flexible so can pass through capillaries

whats the importance of haemoglobin in red blood cells

• enables red blood cells to carry oxygen around the body

• in the lungs, haemoglobin binds to oxygen to become oxyhaemoglobin

• in body tissues oxyhaemoglobin splits up to release oxygen to the cells

what are the minerals that plants take up and why

• magnesium for making chlorophyll

• phospherous to make dna and cell membranes

what do phloem tubes do

transport food both up and down the stem to storage tissues.

what do xylem tubes do

carry water and minerals from the roots up the shoot to the leaves in the transpiration stream

whats translocation

the movement of sugar to all other parts of the plant

whats transpiration

the loss of water from the plant through the evaporation and diffusion of water from a plants surface

whats the transpiration stream

the movement of water through the xylem tissue

why is the transpiration stream constant in a plant

• evaporation and diffusion of water from the leaves create a shortage of water in the leaves

• means more water is drawn up from the rest of the plant through the xylem vessels to replace it

• causes more water to be drawn up through the roots

whats the 4 benefits of the transpiration stream in a plant

1. constant stream of water from ground helps keep plant cool

2. provides plant with constant supply of water for photosynthesis

3. water creates turgor pressure in the plant cells to help support the plant and stop it wilting

4. minerals needed by the plant can be bought in from soil along with the water

how are phloem adapted to their function

• cells are arranged end to end to form phloem tubes with sieve plates inbetween them to allow movement of substances through the plant

how are xylem adapted to their function

thick side walls strengthened by lignin which allows plant to withstand pressure of water moving through the plant

whats a transpiration stream

the flow of water through a plant, from the roots to the leaves, via the xylem vessels.

whats a stomata

Stomata are tiny holes found in the underside of leaves. They control water loss and gas exchange by opening and closing

whats the 3 things transpiration rate affected by

1. increase in light intensity

2. increase in temperature

3. increase in air movement

how is the transpiration rate affected by an increase in light intensity

• brighter the light, greater the transpiration rate

• increases the rate of photosynthesis causing stomata to open and let c02 in

• stomata close when dark as photosynthesis cant happen in the dark

• when stomata are closed water cant escape

how is the transpiration rate affected by an increase in tenperature

• the warmer it gets , faster transpiration happens

• when warm, water particles have more energy to evaporate an diffuse out of stomata

how is the transpiration rate affected by an increase in air movement

• lots if air movement (wind) around leaf transpiration happens faster

• if air around leaf is still water vapour surrounds leaf and dosnt move away

• means high concentration of water particles outside of leaf as well as inside it so diffusion dosnt happen as quickly

• if windy, water vapour is swept away maintaining low concentration of water in the air outside leaf