(P2) Topic 6: Plant Structures And Their Functions Flashcards
Negative of plants making poisons
Uses a lot of energy
Positive of plants making poisons
Less likely to be eaten
Poisons can kill bacteria
How do potatoes respond to the pathogen of potato blight
Produces a chemical
What is digoxin and where is it found
It is a chemical found in foxgloves, which can kill as it affects how the heart beats
What is quinine and what is it produced by
It treats malaria and it produced by chichona trees
What is aspirin and what is it produced by
It treats symptoms of disease such as pain and fever, produced by willow trees
What is a callose
A polysaccharide (a carbohydrate (e.g. starch, cellulose, or glycogen) whose molecules consist of a number of sugar molecules bonded together)
Why is a callose produced
To act as a temporary cell wall in response to stress or damage
What is a polysaccharide composed of
Glucose
Where is a callose produced and through what process
Manufactured at the cell wall through callose synthesis
What is a callose produced in response to
Wounding, infection by pathogens, aluminium, and abscisic acid
The lighter the shade of green, the _ sunlight it gets
More
The smaller the leaf, the _ sunlight the plant gets
More
What is the primary function of leaves
To be the sight of photosynthesis
What is the green pigment in plants
Chlorophyll
How do plants produce food
By trapping sunlight (+other aspects)
Are all plant pigments green and why
No, there are orange, purple, yellow, and red pigments that also play a part in photosynthesis
The orange pigment is called carotenoids
Plants have different pigments to maximise their usage of solar energy that they receive
What kind of reaction is photosynthesis
Endothermic, meaning it needs a catalyst
What is a catalyst
A substance that speeds up a reaction that isn’t used up or changed by the reaction
What is the word equation for photosynthesis
Carbon dioxide + water —— (sunlight and chlorophyll)——> glucose + oxygen
What is the glucose produced by photosynthesis used for
For energy through respiration
How is glucose stored in a plant
As starch
What is the formula equation for photosynthesis
6 CO2 + 6 H2O → C6H12O6 + 6 O2
What is Fick’s Law
Rate of diffusion ∝ (surface area x concentration difference)/ thickness of membrane
Why are leaves wide and flat
To create a large surface area and to absorb as much light as possible
Why are leaves thin
So gasses can reach cells easily
Why do leaves have veins
To carry water to the cells and carry glucose away
Why do leaves have stomata
For gasses to move in and out
What are stomata
Holes on leaves through which gasses move in and out
Where are stomata
The underside of the leaf
Why are stomata on the underside of the leaf
To prevent excess water loss
Why do some plants eat animals
To create their own fertilisers- if there is little nitrogen in the soil, they get nitrogen from animals
What family does the cactus belong to
Xerophite family
Why are there different colours of cactus
For different light intensities
What does albedo mean
How much light reflects off a surface
Why do cacti have spines
The leaves evolved into spines to reduce the surface area so less water can be lost (as they grow in hot environments)
To prevent animals from eating them
What part of cacti contain chlorophyll and what does this cause
The stem, meaning they grow very slowly
Why is the stem of cacti often rounded
To reduce the surface area so less water is lost
Why are the roots of cacti long
To reach water deep down
Why does the stem of cacti store water
To last through droughts
How do bees pollinate flowers
The bee’s hairy bodies accidentally brushes pollen from the anthers onto the stigma
What are the adaptations of insect pollinated flowers to attract insects
Brightly coloured petals
Nectar made at the base of the petals
How do wind pollinated flowers pollinate
Wind carries the pollen away and some of it falls onto the stigmas of other flowers
How are wind pollinated flowers adapted
Anther hangs out of the flower, small and light pollen grains
What kit is needed to test a leaf for starch
Bunsen burner, tripod, gauze, heat-proof mat, tweezers, ethanol, water, test tube, iodine, leaf, beaker
What is the method to test a leaf for starch
1) Boil a beaker of water over a silent blue flame
2) Place a leaf into the beaker for two minutes to break down the cell wall of the leaf
3) Take the leaf out with tweezers
4) Place the leaf into a test tube with ethanol to remove the chlorophyll to make it a fair test
5) Place the test tube into the beaker of water, with the Bunsen burner off as ethanol is highly explosive and ethanol has a lower boiling point than water
6) Remove the leaf when the colour has been removed
7) Add iodine to the leaf- orange= no starch, blue-black= starch
Testing a leaf for starch (simple version)
1) boil
2) leaf into for 2 minutes
3) leaf out
4) with ethanol
5) into beaker, no flame
6) no colour
7) iodine
What do all plant tissues require to survive
Water
What do the xylem and phloem do
Transport water, but in different ways
What practical measures the rate of photosynthesis
Elodea bubbler
What happens in the practical to measure the rate of photosynthesis- steps
1) Pondweed in a conical flask containing a mix of water and sodium hydrogen carbonate
2) Pondweed does photosynthesis and produces bubbles of oxygen
3) The rate of photosynthesis in this experiment can be measured by counting the number of bubbles per minute OR by collecting the oxygen produced in a gas syringe (more accurate)
4) Test if the gas is oxygen
What is the test to prove that a gas is oxygen
Put a glowing split (not lit!!) in a test tube filled with the gas collected and if the split relights, its oxygen
What is the practical to measure the rate of photosynthesis (simple ver)
1) pondweed with water and sodium hydrogen carbonate
2) bubbles
3) count or syringe
4) oxygen?
What is translocation
The movement of assimilates made by plant cells along the phloem
What process occurs in the phloem
Osmosis
What is an assimilate
A complex store in biology, hard to separate the different components
What is the main assimilate that moves along the phloem
Sucrose
Which direction do fluids in the xylem go
Up
Which direction do fluids in the phloem go
Any direction
What is the source
Anywhere sucrose is released into the phloem
What is the sink
Anywhere sucrose is removed from the phloem
Is a leaf in the summer a source or sink
Source- does photosynthesis so it produces sucrose as a byproduct
Is a developing bud a source or sink
Sink- using sucrose, nutrients, and energy to grow
Is an actively growing root tip a source or sink
Sink- uses sucrose, energy, and nutrients to grow
How are assimilates loaded into the phloem
1) The companion cells use ATP to actively transport hydrogen ions int the surrounding tissue
2) This creates a diffusion gradient with a high concentration of hydrogen ions outside the companion cells
3) Hydrogen ions move back into the companion cells using co-transporter proteins and bring sucrose with them
4) This causes the concentration of sucrose in the companion cells to increase
5) Sucrose moves from the companion cells to the sieve tube elements using the plasmodesmata
What is ATP
Energy in cells
Loading assimilates into the phloem (simple version)
1) energetic companion cells move hydrogen into tissue
2) diffusion gradient
3) hydrogen cells move back into companion cells with sucrose
4) conc of sucrose inside increases
5) sucrose moves from companions to the sieve tube
How is marram grass adapted to survive in the hot, windy, dry conditions of a sand dune
A thick, waxy cuticle to prevent excess water loss through evaporation
Trapped air in the centre ensures there is little water lost to high winds (stuck in the centre as water vapour)
Stomata in pits helps to reduce water loss as the water vapour is able to condense on the plant itself
Curled shape ensures that it wont break in high wind
Hairs mean that the water vapour condenses on the leaf
What is transpiration
How water passes up the stem
How do mineral ions enter the plant
Active transport, from the soil into the roots
What is the order of transpiration
1) Water enters the root by osmosis - in the roots
2) Water and ions pass up the xylem - in the roots
3) Transpiration stream - in the stem
4) Water evaporates - from the leaves
What is the transpiration stream
The movement of water through the plant
What are the factors that affect the rate of transpiration
Concentration of water
Temperatures
Surface area of leaf
Wind speed
What is used to measure transpiration
A potometer
What part of the plant grows
The meristem- the other parts of the plant only elongate their cells
What hormone does the meristem make
Auxin
What is I.A.A
A hormone/chemical that makes cells elongate
What is I.A.A destroyed by
Light
What happens if one side of the meristem is in the light and the other is in the shade
The side in the shade will get taller and the side in the light will not and the plant will bend towards the sun (as the I.A.A has been destroyed on the sunny side)
What are hormones
Chemical messengers
What do hormones control in plants
Growth (roots and shoots), seed germination, leaf fall, disease, resistance, fruit formation and ripening, flowering time, and bud formation
What are 3 common plant hormones
Gibberellins
Prostaglandins
Ethylene
What does ethylene do
Controls fruit ripening
What do gibberellins do
Controls fruit development
What do prostaglandins do
flowering, enzyme synthesis, seed germination, and permeability
What is tropism
Growth response to a stimulus
What is phototropism
Growth in response to light
Positive- at the tip, grows towards the light
Negative- at the root, grows away from the light
What is geotropism
Growth in response to gravity
Positive- at the root, grows towards gravity pull
Negative- at the tip, grows away from gravity pull
What is chemotropism
Growth in response to chemicals
Positive- at the root, grows towards chemicals
Negative- at the tip, grows away from chemicals
What is thigmotropism
Growth in response to touch
Positive- at the tip, grows towards touch (coils)
Negative- at the root, grows away from touch
What is hydrotropism
Growth in response to water
Positive- at the root, grows towards water
Negative- at the tip, grows away from water
