Paper 1: Topic 4 Bioenergetics - Photosynthesis (LV) Flashcards Preview

Mrs P's GCSE Biology > Paper 1: Topic 4 Bioenergetics - Photosynthesis (LV) > Flashcards

Flashcards in Paper 1: Topic 4 Bioenergetics - Photosynthesis (LV) Deck (47)
Loading flashcards...

State the word equation for photosynthesis

Carbon dioxide + water → glucose + oxygen


remember to write light and chlorophyll above the arrow between the reactants (left hand side) and products (right hand side)


State the chemical symbol equation for photosynthesis

CO2 + H20 → C6H12O6 + O2


You must be able to write this equation in the correct format for the exam 


Describe the process of photosynthesis

Green plants and algae use light energy to convert carbon dioxide and water into glucose and oxygen.


State the raw materials needed for photosynthesis


Explain how the plant obtains both of these raw materials

  1. Carbon dioxide (obtained from the air when carbon dioxide diffuses into the leaf through the stomata)
  2. Water (absorbed by the root hair cells and then transported up the plant to the leaves in the xylem by transpiration)


Other than the 2 raw materials what else is needed for photosynthesis to occur




Name the waste product of photosynthesis



Define the term endothermic

A chemical reaction that absorbs energy from the environment

In photosynthesis the energy is absorbed from the light and transfered to the chloroplasts 


Is photosynthesis an endothermic or exothermic reaction?



State 5 uses of glucose in plants

1. For respiration to produce ATP

2. Converted to insoluble starch for energy storage

3. Converted to cellulose to make new cell walls

4. To produce amino acids to produce new proteins for growth and repair of tissues and organs

5. To make oils or lipids for energy storage in seeds


What nutrients do plants need to make amino acids?

Glucose (from photosynthesis) and nitrate ions (taken up from the soil by root hair cells)


State 3 reasons why plants store starch

  1. It is does not affect the water potential of the cell
  2. It is insoluble
  3. It stores a lot of energy per molecule


Where do plants store starch?

In their roots, stems and leaves


State 3 factors that affect the rate of photosynthesis

3 from

  • Temperature
  • Light
  • Concentration of carbon dioxide
  • Amount of chlorophyll present


State 3 aspects of light that affect the rate of photosynthesis

  1. Wavelength (not all wavelengths can be used by plants)
  2. Duration (length of time there is light)
  3. Intensity (how much light is available)


Define the term ‘limiting factor’

The variable that limits the reaction from occurring any faster


What are the 4 limiting factors that can affect the rate of photosynthesis?

  1. Temperature
  2. Light
  3. Concentration of carbon dioxide
  4. Quantity of chlorophyll in the leaves


HINT: do NOT say water - this is found in all plants cells and therefore very very rarely a limiting factor


Describe a situation when carbon dioxide may be a limiting factor for photosynthesis

At night when the stomata are closed

This prevent gas exchange occurring in the leaf


Describe a situation when temperature may be a limiting factor for photosynthesis

A cold winter’s day when air temperatures are very low


Describe a situation when light intensity may be a limiting factor for photosynthesis

Night time!

Or a very cloudy day 


Describe a situation when chlorophyll may be a limiting factor for photosynthesis

When the plants are deficient in magnesium (referred to as environmental stress)

If the plant has a disease such as tobacco mosaic virus (reduces the amount of chlorophyll)


What is meant by the term environmental stress

When a plant can’t obtain all the nutrients it requires for healthy growth e.g. lack of mineral ions, lack of water (drought)


How can the rate of photosynthesis be studied

Measure the volume of oxygen produced in a given period of time


How can oxygen production be measured?

  • By the displacement of water using an upturned measuring cylinder filled with water


  • By collecting the gas in a gas syringe


How can you ensure that carbon dioxide is not a limiting factor when investigating the rate of photosynthesis?

Study the rate of photosynthesis using an aquatic plant

Add hydrogen carbonate to the water to ensure an excess of carbon dioxide is available


How can you prevent temperature affecting the rate of photosynthesis if you are investigating the effect of light intensity?

  • Use a heat screen between the plant and the light source e.g. a beaker filled with water to absorb the heat energy emitted from the light bulb


  • Use a set of apparatus that can be immersed in a thermostatically controlled waterbath


At what temperature do photosynthetic enzymes usually become denatured?



Give an example of a situation where photosynthetic enzymes may get denatured

In a greenhouse on a hot, sunny day


Explain why counting bubbles is not an accurate method of measuring the rate of photosynthesis

  • The size and volume of the bubble can vary
  • Bubbles evolve at a very fast rate resulting in inaccurate counting
  • Some bubbles may remain trapped on the underside of the leaves and not rise to the surface for counting


Explain why white light is best used when investigating the rate of photosynthesis in a laboratory

White light covers a wide range of wavelengths of light (~390-700nm) so should result in faster photosynthesis


Describe how to calculate light intensity

1 divided by the distance squared

Light intensity = 1/d2

Decks in Mrs P's GCSE Biology Class (26):