Edexcel GCSE Biology - Topic 6 Exam
Question With Correct Answers
Equation for photosynthesis - ANS6CO2 + 6H2O ------> C6H12O6 + 6O2
Is photosynthesis endothermic or exothermic - ANSendothermic
How is glucose used in plants (5) - ANSRespiration
Stored as starch
Converted to Celulose to use to build cell walls
Use with nitrates to synthesise proteins
Converted to lipids to use as storage
Waxy cuticle (3) - ANSForms a waterproof layer to stop water loss due to photosynthesis
Prevents infection
Clear to maximise sunlight reaching palisade cells
Upper epidermis (2) - ANSthe part of the leaf above the palisades layer that prevents the loss of
water.
Thin and transparent to maximise sunlight reaching palisade cells
Palaside cells (3) - ANSNear top of leaf to increase the rate of photosynthesis
Column shaped so they can be tightly packed
Packed with chloroplasts
Spongy Cells (mesophyll) - ANSContain air space to allow gases to diffuse through leaf
Lower epidermis - ANSprotective layer on the bottom of leaf which contains stomata & guard cells
Guard cells - ANSContain chloroplasts to produce ATP for movement
, Control opening and closing of stomata
Stomata - ANSA microscopic pore surrounded by guard cells in the epidermis of leaves and stems
that allows gas exchange between the environment and the interior of the plant.
How do stomata open and close? - ANSLight - Osmosis into guard cells - turgid - stomata open
Dark - osmosis out of guard cells - flaccid - stomata close
Why are leaves thin - ANSShort distance for carbon dioxide to diffuse into leaf cells
Why do you leaves have a large surface area - ANSTo absorb more light
Give three ways to measure the rate of photosynthesis - ANSRate of oxygen produced
Rate of carbon dioxide uptake
The rate of glucose production
Limiting factor - ANSA factor when in short supply can limit the rate of a process
How does temperature affect photosynthesis - ANSAs the temperature rises, the rate of
photosynthesis increases as the reaction speeds up. However, photosynthesis is controlled by
enzymes. Most enzymes are denatured at high temperatures (40-50 C) so if this occurs the rate of
photosynthesis will fall.
How does light intensity affect photosynthesis - ANSIncreased light intensity will increase the rate of
photosynthesis until it reaches a saturation point.
How does carbon dioxide concentration affect photosynthesis - ANSCO2 is a substrate for an enzyme
controlled reaction, so as CO2 concentration increases, so does photosynthesis rate, but once all the
enzyme active sites are used up, the reaction cannot go faster. A minimum CO2 concentration is
needed for photosynthesis to begin.
What do xylem transport - ANSwater and minerals
Features of xylem (3) - ANSMade of dead cells
Question With Correct Answers
Equation for photosynthesis - ANS6CO2 + 6H2O ------> C6H12O6 + 6O2
Is photosynthesis endothermic or exothermic - ANSendothermic
How is glucose used in plants (5) - ANSRespiration
Stored as starch
Converted to Celulose to use to build cell walls
Use with nitrates to synthesise proteins
Converted to lipids to use as storage
Waxy cuticle (3) - ANSForms a waterproof layer to stop water loss due to photosynthesis
Prevents infection
Clear to maximise sunlight reaching palisade cells
Upper epidermis (2) - ANSthe part of the leaf above the palisades layer that prevents the loss of
water.
Thin and transparent to maximise sunlight reaching palisade cells
Palaside cells (3) - ANSNear top of leaf to increase the rate of photosynthesis
Column shaped so they can be tightly packed
Packed with chloroplasts
Spongy Cells (mesophyll) - ANSContain air space to allow gases to diffuse through leaf
Lower epidermis - ANSprotective layer on the bottom of leaf which contains stomata & guard cells
Guard cells - ANSContain chloroplasts to produce ATP for movement
, Control opening and closing of stomata
Stomata - ANSA microscopic pore surrounded by guard cells in the epidermis of leaves and stems
that allows gas exchange between the environment and the interior of the plant.
How do stomata open and close? - ANSLight - Osmosis into guard cells - turgid - stomata open
Dark - osmosis out of guard cells - flaccid - stomata close
Why are leaves thin - ANSShort distance for carbon dioxide to diffuse into leaf cells
Why do you leaves have a large surface area - ANSTo absorb more light
Give three ways to measure the rate of photosynthesis - ANSRate of oxygen produced
Rate of carbon dioxide uptake
The rate of glucose production
Limiting factor - ANSA factor when in short supply can limit the rate of a process
How does temperature affect photosynthesis - ANSAs the temperature rises, the rate of
photosynthesis increases as the reaction speeds up. However, photosynthesis is controlled by
enzymes. Most enzymes are denatured at high temperatures (40-50 C) so if this occurs the rate of
photosynthesis will fall.
How does light intensity affect photosynthesis - ANSIncreased light intensity will increase the rate of
photosynthesis until it reaches a saturation point.
How does carbon dioxide concentration affect photosynthesis - ANSCO2 is a substrate for an enzyme
controlled reaction, so as CO2 concentration increases, so does photosynthesis rate, but once all the
enzyme active sites are used up, the reaction cannot go faster. A minimum CO2 concentration is
needed for photosynthesis to begin.
What do xylem transport - ANSwater and minerals
Features of xylem (3) - ANSMade of dead cells
