cells

Question 1

multi cellular organisms

Answer 1

they have difficulty coordinating the body, absorbing and transporting materials

Question 2

large organisms

Answer 2

they have many specialised cells which perform a particular function

Question 3

Tissues

Answer 3

a collection of similair cells that work together to perform a particular function e.g. muscle or glandular (allow us to secrete)

Question 4

organs

Answer 4

collection of tissues and systems are collections of organs

Question 5

plant tissues, organ and systems

Answer 5

• leaves, stem, roots, flowers
• leaves carry out photosynthesis
• the stem carries water, minerals up and sugars down to the roots
• roots take up water and minerals from the soil and anchor the plant to the ground
• flowers are the reproductive organ and attract pollinators; fruit disperse seeds

Question 6

structure of a leaf

Answer 6

epidermal layer- transparent cells with no chloroplasts which allows light to penetrate the leaf
palisade layer- lots of chloroplasts; can perform photosynthesis
spongy layer- fewer chloroplasts, spaces between cells so oxygen and co2 can diffuse in and out
lower epidermis- transparent cells with no chloroplasts; allows light to penetrate
guard cells- contain chloroplasts and can make sugars by photosynthesis, regulate gas exchange
stoma- a gap where gas exchange takes place, water vapour and oxygen is produced
xylem- made of tough dead cells so it can transport water, transpiration causes rings of lignin to form in the cell wall of the leaf and the surface tension causes pressure in the xylem that pulls water from the roots and soil
phloem-transports sap;made up of living cells; rigid

Question 7

structure of leaf

Answer 7

palisade cells arranged end on to let sunlight reach the chloroplasts easily
carbon dioxide in air spaces
co2 diffuses from the air through stomata

Question 8

positions of xylem and phloem (vascular bundle)

Answer 8

stem: vascular bundle located around the edge (structural support)
root: vb in centre of root

Question 9

uses of glucose in plants

Answer 9

growth
reproduction
respiration
making fruits
making cell walls

Question 10

testing a leaf for starch (experiment)

Answer 10

1) take a healthy leaf and drop it into boiling water in a water bath for 30 seconds
2) turn off the bunsen burner. remove leaf from water and place it into a boiling tube of alcohol
3) place the boiling tube with alcohol and the leaf into the water bath to boil ethanol. Leave it until all the chlorophyll has been dissolved out of the leaf
4) using forceps remove the leaf and dunk it into the hot water bath until it softens
5) carefully spread the leaf out on a white tile and cover in iodine solution

Question 11

demonstrating the need for co2 in photosynthesis

Answer 11

1) TAKE TWO PLANTS AND PLACE THEM IN BELL JARS
2) leave them for 1 weak and test a leaf from each
3) leaf A ( with water) should show starch present
leaf b (with KOH- absorbs co2) should show no starch present

Question 12

limiting factors of Photosynthesis

Answer 12

light- in the dark a plant can’t photosynthesise-in dim light they can photosynthesise slowly
-rate of photosynthesis increases as the light intensity increases- a plant reaches a point where it cannot photosynthesise any more
CO2- the more CO2 a plant has the faster it will photosynthesise up to a point where it can’t photosynthesise any faster
temperature- plants phtosynthesise slowly at low temperatures-plants photosynthesise faster when it’s warm
Stomata-CO2 passes through the stomata in to the leaf of a plant- if the stomata close then photosynthesis can’t take place-stomata often close when the temperature is really high to prevent too much water from being lost-on a hot day photosynthesis will slow down or stop for a time

Question 13

demonstrating the need for light in photosynthesis

Answer 13

a leaf had a stencil placed , covering part of the leaf and leaving the other part exposed to light. No stencil= light; stencil= no light.iodine was added after a week ,where there was orange there was no light meaning no starch and where there was light the leaf was blue/black meaning there was starch

Question 14

showing the affect of light intensity on photosynthesis

Answer 14

1) take a fresh piece of Canadian pondweed, cut it to 2/3 the length of a boiling tube, with the cut end facing upwards
2) cover the weed with sodium hydrogen carbonate(makes the water co2 rich)
3) place a lamp exactly at a set distance from the tube and leave for 3 minutes to equilibrate
4) count the number of bubbles given off each minute
5) leave for thirty seconds and then record again
6) move the lamp to different distance and repeat

Question 15

investigating the rate of respiration and photosynthesis

Answer 15

Hydrogen carbonate indicator solution is used to detect the relative concentration of CO2 in a solution
red=atmospheric CO2
purple= no CO2
yellow= high CO2
Tube A: animal only; yellow; animal gives off CO2 during respiration
Tube B: plants only; purple; plant absorbs CO2 during photosynthesisTube
C: plants and animal; red; plant absorbs CO2 and animal releases CO2 so there will be some CO2 leftTube
D: no plants or animals; red; nothing to absorb or produce CO2 so the CO2 levels will remain atmosphericTube
E: no light & plant only; yellow because plants respire which gives off CO2 and there is no light so the plant can’t photosyntheise

Question 16

Stomata

Answer 16

• lower epidermis has a number of pairs of guard cells which surround each stomata
• guard cells contain chloroplasts to perform photosynthesis
• The stomata allows gases to pass in and out of the leaf- the upper epidermis has less stomata than the lower epidermis because the upper surface is facing the sun so the water would evaporate very quickly; the leaf needs to exchange gases but doesn’t want too lose too much water by evaporation
• cells absorb water through osmosis
• as they swell up and become more turgid, they curve away from each other, opening the stomata
• during the night the stomata close to prevent water loss
• during the day they open to allow gas exchangeleaf could wilt if the plant loses too much water as the cells become flacid

Question 17

transpiration

Answer 17

the loss of water vapour from plants through stomatawater moves by osmosis from cell to cell in the xylemroot hairs increase surface arearoot hair cells have a lot of mitochondria for respiration to fuel active transport which moves minerals into the leaf

Question 18

transpiration stream

Answer 18

water is constantly drawn up through the plant , pulling water and minerals towards he leavesdriven by evaporation at stomata which lowers concentration in the air spaces. water is drawn out of cells. This pulls water up the xylem

Question 19

how is the xylem adapted to move water up the plant?

Answer 19

• no end walls so xylem forms a long tube- large lumen; less friction- walls have lignin which makes them water proof

Question 20

demonstrating transpiration through xlem

Answer 20

• celery in a beaker with eosin at the bottom ( red dye)- celery turns red after 24 hours
  measuring the rate of transpiration; potometer

Question 21

factors which affect transpiration

Answer 21

temperature; affects evaporation
light intensity; affects stomata opening or closing
wind speed; wind will blow most air away from the stomata thus increasing water loss
humidity; dry air will increase rate s the concentration gradient of water between the leaf and the air will be steeper

Question 22

investigating how different environmental conditions affect the rate of transpiration

Answer 22

• dark and humid - transpired the least- stomata closes when it is dark and very warm
• humid and light- third lowest
• normal environment- second highest- nothing to affect the rate of transpiration
• hot and windy - highest

Question 23

phloem

Answer 23

• carries products of photosynthesis up and down the plant. glucose is converted into sucrose and is dissolved in the sap that travels through the plant- sucrose ca e delivered to roots, bbuds, flowers, new leaves and fruit