11.1 Overview of photosynthesis

Question 1

What is the site of photosynthesis in eukaryotic plants

Answer 1

. The leaf, and chloroplasts are the cellular organelles within it where photosynthesis occurs

Question 2

Adaptations of Leaf are:

Non overlapping leaves
wide leaves
Thin leaves

Explain

Answer 2

Non overlapping leaves mean it stops some leaves being shadowed so no sun lands on them for photosynthesis

Wide leaves gives large surface area to absorb as much sunlight as possible

Thin leaves mean light is absorbed in the first few micrometres of the leaf and the diffusion distance for gases is kept short

Question 3

Adaptations of Leaf are:

Transparent waxy cuticle
Numerous stomata that respond to light intensity
Air spaces

Answer 3

Transparent waxy cuticle and epidermis let light through to the photosynthetic mesophyll cells beneath

Numerous stomata means more gas exchange can occur as guard cells can open and close them in response to sunlight.
They are all only a short diffusion pathway from a mesophyll cell also

Many air spaces in lower mesophyll allow for rapid diffusion in the gas phase of carbon dioxide and oxygen

Question 4

What does xylem do
Phloem?

Answer 4

Brings water to leaf cells
Phloem carries away glucose made by photosynthesis

Question 5

Equation for photosynthesis

Answer 5

6CO2 + 6H2O —> C6H12O6 +6O2

With light above the arrow

Question 6

What are the layers on the cross section of a leaf

Answer 6

. Upper epidermis
. Upper mesophyll (contains chloroplasts)
. Spongy mesophyll (air spaces)
. Lower epidermis
. Stomata controlled by guard cells

Question 7

Structure of chloroplast

Answer 7

.Outer and inner membrane
. Stacks of thylakoids are called Grana
. Stroma is fluid in the organelle

Question 8

What is photosynthesis

Answer 8

. Complex metabolic pathway, and process of energy transferral in which some energy in light is conserved in the form of chemical bonds

Question 9

What are the 3 stages of photosynthesis

Answer 9

1) Capturing of light energy
2) The light-dependant reaction
3) The light independent reaction

Question 10

What happens in light dependent reaction

Answer 10

. Some light energy absorbed is conserved in chemical bonds.

So during this process an electron flow is created by the effect of light on chlorophyll, causing water to split by autolysis into protons, electrons and oxygen

Products are NADP, ATP and oxygen

Question 11

What happens in light independent reaction

Answer 11

These protons (H+) ions are used to make sugars and other organic molecules

Question 12

What are thylakoids

Answer 12

Where light dependent reaction occurs, there is chlorophyll in them.
Some thylakoids have tubular extensions to join them to adjacent grana

Question 13

What is stroma

Answer 13

Fluid filled matrix where light independent stage of photosynthesis occurs