Photosynthesis Flashcards
What is photosynthesis?
an endothermic reaction where energy is transferred from the environment to the chloroplasts by light from the sun and glucose is produced
What is a stomata?
holes on the underside of the leach which open and close to allow for gas exchange
What is spongy mesophyll?
a tissue found in plant leaves that is specialised for gas exchange by having air spaces that allow diffusion of gases to happen quicker
What are stomata?
small holes found in the lower epidermis that open and close because of guard cells. they control water loss by closing at night and allow diffusion of CO2 and O2.
What is the job of the waxy cuticle?
reduces evaporation of water but allows light to pass through because it is transparent
Where is the waxy cuticle?
on top of the upper epidermis that is insoluble, so the waxy cuticle waterproofs the leaf
What is the palisade mesophyll?
a tissue found in plant leaves carry out photosynthesis
How are the palisade mesophylls specialised to carry out photosynthesis?
vertically packed to capture more sunlight and store more chloroplasts
How might a leaf be specialised for photosynthesis?
large surface area and being thin to absorb maximum sunlight. by increasing the number of stomata, carbon dioxide can diffuse quicker for photosynthesis
What feature of the upper epidermis means the leaf is specialised for photosynthesis?
the upper epidermis is transparent so light is allowed to penetrate the mesophyll
What is the function of the xylem?
the xylem transports water absorbed by roots into the leaves.
How are stomata specialised for photosynthesis?
allow gases to diffuse into air spaces of leaf, this provides a short diffusion distance for carbon dioxide
What is the function of the phloem?
phloem vessels transport sugars made in photosynthesis to other parts of the plant
What are the uses of glucose in plants?
makes other biological molecules
- used to make cellulose (cell walls)
- used to make nucleotides (DNA)
- used to make protein (enzymes)
OR make chlorophyll
Photosynthesis transfers light energy into what?
chemical energy which is then used for respiration and making other biological molecules
What does the plant require to make these biological molecules?
mineral ions
What is the use of nitrates in the plant?
making amino acids (CHON), and nucleic acids (CHONP) and therefore proteins/DNA/RNA
What is the deficiency of nitrates in plants?
stunted growth
What is the use of magnesium ions in the plant?
make chlorophyll
What is the deficiency of magnesium in plants?
yellow leaves
What is the use of phosphate ions in the plant?
make nucleic acid, part of cell membrane
What is the deficiency of phosphate ions in the plant?
poor root growth, purple younger leaves
What are the factors affecting rate of photosynthesis?
carbon dioxide - substrates
light intensity - energy
temperature - kinetic energy - enzymes
What is STEP 1 when testing for starch in a leaf?
heat boiling water in a beaker then turn off bunsen
What is STEP 3 when testing for starch in a leaf?
place the leaf on a white tile and cover in iodine solution
What is STEP 2 when testing for starch in a leaf?
transfer leaf in test tube in ethanol (flammable) into the beaker and soften the leaf
What is STEP 4 when testing for starch in a leaf?
the leave must be destarched for 24 hours in the dark because it means any starch was produced from the glucose made in photosynthesis during your experiment
What is SHOWN when testing for starch in a leaf?
light is required - one leaf is covered with foil
chlorophyll is required - a variegated leaf is used and starch is only produced in certain places
carbon dioxide is required - one leaf is in an enclosed plastic bag with soda lime which absorbs carbon dioxide
How can you investigate the factors affecting the rate of photosynthesis?
a length of pondweed is added to a beaker and the number of bubbles released is counted for one minute.
- distance between bench and lamp changed to vary light intensity
- collecting gas in an inverted measuring cylinder and measuring the volume of oxygen is more accurate
