Plants Flashcards
Photosynthesis
Conversion of light energy to chemical energy
Basis of all food chains
Production of complex organic compounds from simple inorganic compounds
6CO2+6H2O=>C6H12O6+6O2
Factors that affect rate of photosynthesis
Light
CO2
Temp
How light affects photosynthesis
Increase light, increase rate up to a point
Only a certain amount of chloroplasts
Too much light, increased transpiration
Too much water loss leads to stomata closing, p stops as too much UV damages plants
How CO2 affects rate of photosynthesis
Increase CO2, increase p up to a point
Amount of CO2 is fixed at 0.04%
Greenhouses can be pumped with CO2
How temp affects rate of photosynthesis
Higher temp, increased rate of p
If above 40C, rate decreases, enzymes denature
Features CO2 diffuse from air into chloroplasts
Open stomata, CO2 diffuses in
Air spaces in spongy mesophyll
LSA
Feature of leaf for sunlight to get into palisade cell
Transparent upper epidermis
Tightly packed palisade cells full of chloroplasts
LSA
Adaptations of leaf
LSA Thin leaves Leaves on leaf stalk Waxy cuticle Stomata Transparent upper epidermis Palisade layer with elongated cell Spongy mesophyll with air spaces Vascular tissue close by
LSA of leaf
More sunlight absorption
Thin leaves
Shorter distance for light, water and CO2 to travel
Leaves grow on leaf stalk
Orientate themselves for max light absorption
Waxy cuticle
Waterproof
Barrier to microbes
Reduce water loss by evaporation
Stomata
Gas exchange
Transparent upper epidermis
Allows light through to palisade cells
Palisade layer with elongated cell
Tightly packed
Full of chloroplasts
Chloroplasts can move in cell
Spongy mesophyll with air spaces
Gas exchange between atmosphere and leaf cells
Vascular tissue close by
Transport of water to cells from root
Transport of products of photosynthesis away from leaf
Mineral ions
Nitrate, amino acids Stunted growth Magnesium, chlorophyll Yellow leaves Phosphate, respiration, growth Poor growth Potassium, respiration, photosynthesis Discoloured leaves
Experiments to investigate photosynthesis
Pondweed under water, factors varied
Lamp distance, baking powder added,
White leaves plant tested against green leaves plant
Gas given off, bubbles counted
Speed of photosynthesis shown under different conditions
Investigation to see if starch is produced in photosynthesis
Leave in dark for 24hrs, use up starch for respiration
Remove one leaf, boil, burst cell wall and cell membrane
In ethanol, dissolve chlorophyll
In cold water, leave to be pliable
White tile, iodine
Black=starch
Respiration and photosynthesis
Resp, continuous process
Photo, light dependant
Net output at night, CO2
Leaf adaptations for gas exchange
Thin
Stomata at lower epidermis
Guard cells
Thin leaves
Gases diffuse in quickly
Stomata at lower epidermis
Diffusion of gases
Guard cells
Allow gases in
Stomata and gas exchange
Stomata, holes
Guard cells, regulate opening and closing of stomata, allow CO2, O2 exchange between leaf, atmosphere
GC, absorb water, turgid, open
Flaccid, close
Investigations of light on net gas exchange from leaf
Hydrogen carbonate indicator
Leaf to bung, put tube in different light intensities
Observe colour change
Plant response of stimuli
React to environmental changes, temp, light Receptors detect change Effectors carry out response Response, auxin, growth Phototropism, geotropism
Auxin
Growth hormone
Produced in tip
Affects zone of elongation
Geostropism
Root, positive
Auxin falls due to gravity, inhibits growth
Shoots, negative
Phototropism
Stem, positive Auxin likes the shade Stimulates growth on shaded side Elongates Points towards sun
Insect pollination
Scent Small amount of pollen Heavy pollen Large colourful petals Nectaries Small anthers Sticky pollen Small stigmas
Wind pollination
Light pollen Pollen, smooth outer walls Green, small petals No nectaries No scent Large feathery stigma out of flower Large amount of pollen Large hanging anthers
Pollination, fertilisation
Pollen grain on stigma
Tube grows from 1 pollen grain pore, moves along style towards egg sac
1 pollen grain nuclei called tube nucleus controls tube growth
Tube growth towards micropyle
Tube nucleus joins other nuclei in egg sac
Become endosperm
Fertilisation, zygote formed
Flower fades, plant produces fruit
Conditions for seed germination
Water
Warm temp
Oxygen for resp
Germinating seeds
Fertilised ovule, seed Ovary, fruit Zygote develops embryonic plant with radicle root and plumule Ovule contains cotyledons, food store Ovule wall, testa, seed coat Ovary wall, fruit coat
Asexual reproduction
1 parent Vegetative Root, leaf, stem grow into new plants Genetically identical Runners, strawberry Rhizomes, iris Corm, crocus Bulb, onion 2nd stem extends, specialise in root cells, daughter plant Cuttings in auxin, encourage ends, roots, placed in soil
Sexual reproduction
2 parents
Genetically unidentical
Gametes
Plant yield
Control all limiting factors, for optimum conditions
Polythene tunnels
Increased CO2 and temp and crop yield
Polythene tunnels, increase heat, CO2
Reactions happen faster in increased heat and increased CO2
P produces energy, used for growth, higher yield
Fertiliser, crop yield
NPK
Amino acids
Respiration
Enzymes
Pets control
Eat crops, cannot be sold
Pesticides reduce pests that reduce yield
Chemical pesticides
Easy to apply Pests develop resistance Can kill helpful organisms too Poisonous to other organisms Bioaccumulation damage other organisms Can be adjusted for problems and soil type
Biological pesticides
No poison No resistance May become a pest itself Difficult to apply May kill helpful organism Not suitable for all
