Photosynthesis

Question 1

how do plants make their own food?
what do they produce?

Answer 1

through photosynthesis
-glucose

Question 2

which other organisms can photosynthesise?

Answer 2

algae

Question 3

what is biomass?

Answer 3

the dry mass of an organism

Question 4

how will plant biomass be affected because of photosynthesis?

Answer 4

it will increase

Question 5

what is the word and symbol equation for photosynthesis?

Answer 5

carbon dioxide + water -> oxygen + glucose
6CO2 + 6H20 -> 6O2 + C6H12O6

Question 6

which two components (non physical) are also required for photosynthesis?

Answer 6

light and chlorophyll

Question 7

which type of reaction (exothermic or endothermic) is photosynthesis?
-why?

Answer 7

-endothermic reaction
-it requires light energy (to react carbon dioxide and water to produce glucose and oxygen.)

Question 8

what happens to light energy within a leaf?

Answer 8

it is absorbed by the green pigment chlorophyll (within the chloroplasts)

Question 9

why are plant leaves important within a plant?

Answer 9

they are the main organ for photosynthesis

Question 10

where does the required carbon dioxide come from?
-how does it enter a leaf?

Answer 10

-the air.
-through the stomata

Question 11

how does water enter the plant?
how it is then transported to the leaves?

Answer 11

• through the roots, and is transported to the leaves in the xylem.

Question 12

what are the produced oxygen and glucose used for within a plant?

Answer 12

respiration

Question 13

what are the three main ways of measuring the rate of photosynthesis?

Answer 13

-rate of oxygen production (number of bubbles or volume of oxygen gas given off in a set time)
-rate of carbon dioxide uptake
-rate of glucose production

Question 14

which factors can affect the rate of photosynthesis? (3)

Answer 14

light intensity
carbon dioxide concentration
temperature

Question 15

describe the relationship between photosynthetic rate and light intensity (2)

what in particular is the photosynthesis rate proportional to?

Answer 15

-increasing the light intensity increases the rate of photosynthesis,
-until a limiting factor - becomes in short supply

directly proportional to the light intensity until another factor becomes limiting.

Question 16

what happens at very high light intensities? why is this unlikely to happen in the wilderness?

Answer 16

photosynthesis is slowed, but these light intensities do not occur in nature.

Question 17

describe the relationship between carbon dioxide concentration and the photosynthetic rate. (3)

Answer 17

-Carbon dioxide is one of the reactants in photosynthesis.
-If the concentration of carbon dioxide is increased, the rate of photosynthesis will therefore increase.
-At some point, another factor may become limiting (this is shown by the plateau -flattened section- of the graph)

Question 18

what are the chemical reactions involved in photosynthesis controlled by?
what does this mean? (in terms of what they are affected by)

Answer 18

enzymes
-they are affected by temperature

Question 19

describe the relationship between temperature and photosynthetic rate. (3)

Answer 19

-At low temperatures, the rate of photosynthesis is limited by the number of collisions between enzymes and substrate.
-As temperature increases the number of collisions increases, therefore the rate of photosynthesis increases.
-However, at high temperatures, enzymes are denatured and this will decrease the rate of photosynthesis.

Question 20

describe the relationship between photosynthetic rate and other (multiple) factors. (4)

Answer 20

-the rate of photosynthesis increases until factors becoming limiting
-if (factor) is increased, the rate increases further, and then another factor becomes limiting
-the rate can be increased further if the temperature is increased
-the rate increases again until another factor becomes limiting

Question 21

what is the equation for the inverse square law?

Answer 21

L.I = 1/distance^2

Question 22

explain why light intensity is directly proportional to photosynthetic rate? (2)

Answer 22

because photosynthesis is an energy requiring , endothermic, reaction.
-more light energy will increase the rate at which oxygen is given off so more bubbles of oxygen will be produced per minute.

Question 23

why is light intensity inversely proportional to distance?

Answer 23

as the distance away from a light source increases, light energy becomes spread over a wider area.

Question 24

why must you be careful with the x axis of 1/d^2 graphs? (2)

Answer 24

the x-axis is values of 1/d^2. It is not of light intensity.

1/d^2 is proportional to light intensity.

Question 25

what is the function of a leaf?

what are leaves the sources of? (what are they referred to as?)

Answer 25

to photosynthesise

all food on Earth- they are producers