Nutrients in plants Flashcards
Describe the process of photosynthesis [4]
Chlorophyll in chloroplast to absorb light energy and convert to chemical energy [1]
Take in CO2 through stomata via diffusion down the concentration gradient from the environment into the leaf [1]
With the chemical energy, water and CO2 is synthesised / combined to form glucose and oxygen is released. [1]
*must state the chemical equation for photosynthesis with labels on arrow[1]
Describe the fates of the glucose after it’s synthesized in the leaf. [4]
Excess glucose converted to starch and store in the leaf
Convert into sucrose to load into phloem via active transport to transport to other parts of the plant via translocation
Combine with nitrates in mineral salt to form amino acids
Convert to fats to be stored
Used in aerobic respiration to release energy for cellular activities
Explain how rate of photosynthesis can be affected by: Temperature [4]
Note: data required for graphical / table result analysis
When the temperature is low, rate of photosynthesis is low as enzymes are inactive. [1]
There is an increased in the rate of photosynthesis due to increased kinetic energy of enzymes that increase chance of successful collisions to form more enzyme substrate complex to form products. [1]
Rate of photosynthesis is the highest as it is the optimum temperature and the enzymes are most active. [1]
Fall in the rate of photosynthesis beyond optimum temp as enzyme is denatured due to deformed three dimensional shape of active site. [1]
Explain how rate of photosynthesis can be affected by: light intensity [3]
Increase; More chlorophyll activated to convert more light E to chemical E[1] , rate of photo increases to synthesize more glucose [1]
Until optimum intensity is reached, reaction is maximum, light is no longer limiting [1]
Explain how rate of photosynthesis can be affected by: Carbon dioxide concentration [3]
Increase; higher substrate concentration [1]; rate of photo increases to synthesize more glucose [1]
Until maximum rate of reaction is reached when all the enzymes are saturated, CO2 conc is no longer limiting [1]
Describe the general mechanism of stomata opening during the day [6]
Glucose formed in photosynthesis [1] release energy through aerobic respiration[1]
Conc. of potassium ions (K+) increases in the guard cells via active transport.[1]
The water potential of cell sap of the guard cells is lowered.[1]
Net movement of water molecules from adjacent epidermal cells into guard cell by osmosis.[1]
Guard cells swell and become turgid. [1]
This causes the guard cells to become curved and pull the stoma open [1].
OR (reverse)
At night, no photosynthesis to produce glucose, no active transport to maintain conc gradient of K+ ions. [1]
conc. of potassium ions (K+) in guard cell is higher than outside, diffuse out down the conc gradient [1]
The water potential of the cell sap of guard cells is increased.[1]
Net movement of water molecules from guard cell out to adjacent epidermal cells by osmosis.[1]
Guard cells are plasmolysed and become flaccid. [1] This causes the guard cells to close the stoma pore [1].
Describe and explain how the leaf is adapted for photosynthesis [6]
Petiole / leaf stalk ;
o holds leaf in position to absorb maximum light energy [1]
Thin broad lamina / leaf blade ;
o increase surface area to volume ratio for maximum absorption of light
energy [1]
Waxy cuticle ;
o prevents excess water loss / reduces water loss through evaporation from the leaf / transparent for maximum light to enter the leaf [1]
Stomata present in epidermal layers/lower epidermis ;
o Allow carbon dioxide to diffuse in as raw materials for photosynthesis and oxygen to diffuse out of the leaf [1]
Chloroplasts containing chlorophyll ;
o Chlorophyll absorbs and transforms light energy to chemical energy used
In the manufacture of sugars [1]
More chloroplasts in the upper palisade tissue/in palisade mesophyll cells ;
o More light energy can be absorbed near the leaf surface [1] Interconnecting air spaces ;
o Allow rapid diffusion/ gaseous exchange of carbon dioxide / oxygen into and out of mesophyll cells [1]
Veins containing xylem and phloem situated near mesophyll cells ;
o Xylem transport water and dissolved mineral salts from roots to mesophyll
cells / phloem transport sucrose and amino acids away from the leaf [1] Presence of guard cells
o Regulate / control the opening and closing of stomata for gaseous exchange
thin layer of moisture on mesophyll cells
o Allow gases to dissolve for diffusion to occur
Outline the pathway of a carbon dioxide molecule from the time it enters the leaf until it eventually becomes part of a glucose molecule in a leaf cell. [5]
Photosynthesis used up / depletes CO2 as raw material, causing lower conc in the leaf [1].
CO2 diffuse from environment down concentration gradient via the stomata into intercellular spaces [1]
CO2 dissolve in the thin film of moisture on the spongy mesophyll cell [1]
Dissolved CO2 diffuse into the cell and into the chloroplasts. [1]
Combines with hydrogen ions and chemical energy to reduce into glucose during photosynthesis [1] OR Combines with water in the presence of light to synthesize glucose during photosynthesis [1]
Describe and explain the concept of ‘compensation point’. [4]
Rate of photosynthesis can vary according to light intensity which increases during the day and decreases at night. Rate of respiration stays constant throughout the day [1]
Compensation point is when the rate of photosynthesis becomes equal to the rate of respiration [1]
which means that the amount of O2 given out during photosynthesis is equal to the amount of O2 taking in during respiration. Which also means that the amount CO2 taken in during photosynthesis is equal to the amount of CO2 given out during respiration[1].
thus there is no net movement of O2 and CO2 via the stomata between the atmosphere and the leaf through the process of diffusion [1].
Describe what may happen to the waste products of respiration in a plant [5]
Co2
Used as raw material for photo in chloroplast in the presence of light to synthesize glucose by combining with water molecules
Diffuse out of leaf via stomata down the conc gradient
H2O
Used as raw material for photo in chloroplast in the presence of light to synthesize glucose by combining with CO2
Evaporate to form W.V and diffuse out of leaf via stomata down conc gradient during transpiration
Maintain turgidity of plant cell for mechanical support
Explain how most forms of life are dependent on the processes involved in plant nutrition, including reference to bacteria. [6]
CO2
Removal of atmosphere CO2 as raw material for photosynthesis, excess CO2 in the air is toxic when accumulated
Maintain carbon cycle by taken in atmtmospheric CO2 and convert to organic substance during photosynthesis to pass down the food chain.
O2
Release of O2 as product of photosynthesis. Living things use O2 for aerobic respiration to oxidise glucose to release E for cellular activities
Bacteria require O2 for decomposition of dead organic matter to inorganic substance for recycling of nutrients / nutrient cycle.
glucose
during photosynthesis, convert light energy to chemical energy in synthesizing glucose to be passed down the food chain
Used as energy source to release E for cellular activities OR used in synthesizing protoplasm for growth and repair
describe and explain how environment in a green house can be regulated to optimise vegetation growth. [6]
Light – install lights to increase light intensity for higher rate of photo to produce glucose [2]
Temp- install heater to regulate optimum temp for maximum rate of enzyme activity for photo [2]
CO2 conc- install air conditioner to increase CO2 conc for more raw materials for photo to produce more glucose [2]
Water – install irrigation system to optimize water supply for more raw materials for photo to produce more glucose [2]
Compare between plants grown in bright and shady conditions. Suggest and explain possible differences in their adaptations for survival. [4]
Shady plants have bigger / broader leaves than bright condition plants [1] more SA to absorb more light for photo [1]
Shady plants have more conc of chloroplast than bright condition plants [1] to absorb more light and convert to chemical E for photo [1]
