photosynthesis (paper 1)

Question 1

define a leaf

Answer 1

plant organ made of different specialised tissues

Question 2

define photosynthesis

Answer 2

series of endothermic chemical reactions which occur in plant cells which contain chloroplasts

Question 3

word equation for photosynthesis

Answer 3

carbon dioxide + water = glucose + oxygen

Question 4

3 conditions needed for photosynthesis to occur

Answer 4

warmth
light
chlorophyll

Question 5

4 ways in which plants use glucose

Answer 5

• respiration to transfer energy from glucose to other molecules
• converted into insoluble starch for storage
• produces lipids or oils for storage in seeds + tubers
• produces cellulose which strengthens cell walls

Question 6

presence of molecules in starch negative result

Answer 6

yellow-brown

Question 7

presence of molecules in starch positive result

Answer 7

blue-black

Question 8

presence of molecules in glucose negative result

Answer 8

blue

Question 9

presence of molecules in glucose positive result

Answer 9

yellow
green
orange
brick-red

Question 10

presence of molecules in proteins negative result

Answer 10

blue

Question 11

presence of molecules in proteins positive result

Answer 11

lilac

Question 12

presence of molecules in lipids negative result

Answer 12

one layer with red colour distributed easily

Question 13

presence of molecules in lipids positive result

Answer 13

red layer forms on the top of solution (2 layers form)

Question 14

how would you identify what type of food molecule a sample contains? (4)

Answer 14

1. get piece of food and break up using pestle + mortar
2. transfer the ground up food to a beaker and add some distilled water
3. give mixture good stir with glass rod to dissolve some of the food
4. filter solution using funnel lined with filter paper to get rid of solid bits of food

Question 15

explain how you would use Benedict’s test to test for sugars (5)

Answer 15

1. prepare food sample and transfer 5cm^3 to test tube
2. prepare water bath so that its set to 75C
3. add some BS to test tube (10 drops) using a pipette
4. place test tube in water bath using test tube holder and leave in for 5 mins. make sure test tube pointing away from you
5. if food sample contains reducing sugar the solution in test tube will change from blue to green yellow or brick-red

Question 16

explain how you would you iodine solution too test for starch (2)

Answer 16

1. make food sample an transfer 5cm^3 of sample to a test tube
2. add few drops of iodine solution an gently shake tube to mix contents. if sample contains starch, colour of solution will change from browny-orange to black or blue-black

Question 17

explain how you would use burets test to test for proteins (3)

Answer 17

1. prepare sample of your food and transfer 2cm^3 of it to test tube
2. add 2cm^3 of BS to sample and mix contents of tube by gently shaking it
3. if the sample contains protein, the solution will change from blue to pink or purple (remain blue if no proteins present)

Question 18

explain how you would use the Sudan III test for lipids (3)

Answer 18

1. prepare sample of food your testing an transfer 5cm^3 into a test tube
2. use pipette to add 3 drops of SS solution tot eat tube an gently shake tube
3. if sample contains lipids mixture will separate out into 2 layers. Top layer = bright red only if lipids are present

Question 19

name the substance that plants use to strengthen cell walls

Answer 19

cellulose

Question 20

2 substances used for photosynthesis

Answer 20

glucose
oxygen