3.1 Photosynthesis

Question 1

Where does photosynthesis take place

Answer 1

In the chloroplasts

Question 2

What are the adaptions of a leaf for photosynthesis

Answer 2

• large surface area
• the arrange plenty of leaves
• thin
• transparent cuticle and epidermis
• long, narrow upper mesophyll cells packed with chloroplasts
• numerous stomata
• stomata that open and close
• many air spaces
• a network of xylem

Question 3

(Adaptations for ps) why do leaves have a large surface area

Answer 3

To collect as much sunlight as possible

Question 4

(Adaptations for ps) what does the arrangement of the leaves minimise

Answer 4

Overlapping so avoids shadowing one leaf by another

Question 5

(Adaptations for ps) why is a leaf thin

Answer 5

To keep the diffusion distance short and most light is absorbed by the first few mm

Question 6

(Adaptations for ps) what does the transparent cuticle and epidermis ensure

Answer 6

That light is let through to the photosynthetic mesophyll cells beneath

Question 7

(Adaptations for ps) why are the upper mesophyll cells long and narrow and packed with chloroplasts

Answer 7

To collect sunlight

Question 8

(Adaptations for ps) why are there numerous stomata

Answer 8

For gaseous exchange

Question 9

(Adaptations for ps) what is the importance of stomata that open and close

Answer 9

They can change in response to changes in light intensity

Question 10

(Adaptations for ps) what is the importance of many air spaces in the lower mesophyll layer

Answer 10

To allow the diffusion of carbon dioxide and oxygen

Question 11

(Adaptations for ps) what does the network of xylem do

Answer 11

Brings water to the leaf cells

Question 12

(Adaptations for ps) what does the phloem do

Answer 12

Carries away the sugars produced in photosynthesis

Question 13

What does photosynthesis produce

Answer 13

Oxygen by releasing it from water molecules

Question 14

What is the equation for photosynthesis

Answer 14

6CO2 + 6H2O ——————–> C6H12O6 + 6O2

Light

Question 15

What is the word equation for photosynthesis

Answer 15

Carbon dioxide + water ——————-> glucose + oxygen

Light

Question 16

What are the 3 main stages of photosynthesis

Answer 16

1) capturing the light energy
2) the light-dependant reaction
3) the light-independent reaction

Question 17

How is light energy captured during photosynthesis

Answer 17

By chloroplast pigments such as chlorophyll

Question 18

What happens in the light-dependant reaction

Answer 18

Light energy is converted into chemical energy. During the process an electron flow is created by the effect of light on chlorophyll and this causes water to split (photolysis) into protons electrons and oxygen.

Question 19

What are the products of the light-dependant reaction

Answer 19

Reduced NADP, ATP and oxygen

Question 20

What happens on the light independent-reaction

Answer 20

These protons(hydrogen ions) are used to reduce carbon dioxide to produce sugars and other organic molecules

Question 21

Chloroplast structure

Answer 21

• typically disk shaped
• 2-10 um long and 1 um in diameter
• surrounded by a double membrane

Question 22

What are the 2 distinct regions found inside chloroplasts

Answer 22

The grana and the strong

Question 23

Grana structure

Answer 23

Stacks of up to 100 disk like structures called thylakiods

Question 24

Stroma structure

Answer 24

A fluid filled matrix where the light-independent stage of photosynthesis takes place. Filled with a number of other structures eg starch grains

Question 25

What is found within the thylakiods

Answer 25

The photosynthetic pigment called chlorophyll

Question 26

What are inter-gran all lamallae

Answer 26

Thylakiods that have tubular extensions that join up with thylakiods in the adjacent grana

Question 27

Draw the structure of a leaf

Answer 27

Page 33

Question 28

Draw the cross section of a leaf

Answer 28

Page 33

Question 29

Draw a chloroplast structure

Answer 29

Page 33