12.3 Flashcards
what happens during photosynthesis
carbon dioxide and water are the substrates for photosynthesis, chlorophyll absorb light energy and converts light energy to chemical energy stored in glucose
how is rate of photosynthesis affected
light intensity, carbon dioxide concentration, temperature
how does light intensity affect rate of photosynthesis
a plant cannot photosynthesise very fast even if there is plenty of water and carbon dioxide, increasing light intensity increases rate of photosynthesis until constant rate is reached
how does temperature affect rate of photosynthesis
increasing temp to optimum temp increases rate of photosynthesis, increasing temp beyond optimum temp decreases rate of photosynthesis bc of enzyme denaturing
how does carbon dioxide concentration affect rate of photosynthesis
even if there is plenty of light, plant cannot photosynthesise if it has insufficient carbon dioxide, increase carbon dioxide concentration increases rate of photosynthesis until constant rate is reached
what is the importance of photosynthesis (3 points)
makes chemical energy available to animals and other organisms, removes carbon dioxide and produce oxygen, energy from fossil fuels comes from sun through process of photosynthesis
why does the stem swell when phloem is cut out?
food substances from the leave cannot reach the leaves below cut region, sucrose and amino acids accumulate in region above cut region
what is transpiration
loss of water vapour from aerial parts of plant, mainly through the stomata of leaves
how to measure rate of transpiration
using potometer to directly measure rate of absorption of water by plant
what are the factors affecting transpiration rate (4 points)
humidity, wind or air movement, temperature of air, light intensity
how does humidity affect transpiration
decrease rate, water vapour concentration gradient is less steep
how does wind and air movement affect transpiration
increase rate, steeper water vapour concentration gradient
how does temp affect transpiration
increase accumulation of water vapour in intercellular air spaces of leaf, water vapour concentration gradient between intercellular air spaces in leaf and surrounding atmospheric air is steeper
how does light intensity affect transpiration
affect size of stomata. in sunlight, stomata open and become wider, increase rate if transpiration
what is wilting
excessive transpiration, water loss exceeds water absorption
