bioenergetics (T4) Flashcards
what cellular structures are specific to plants and not animals
chloroplasts, vacuole, cell wall
function of a root hair cell
absorb water and dissolve mineral ions from the soil
adaptations of root hair cell
- special shape with long cytoplasmic extension (root hair)
- large permanent vacuole
- many mitochondria
how do the adaptations of a root hair cell help
- gives a large SA for more efficient absorption
- store large amounts of water to help maintain conc. gradient
- allow lots of respiration to release energy for the active transport of minerals
function of a palisade cell
maximum photosynthesis
adaptations of a palisade cell
- lots of chloroplasts
- rectangular shape
how do the adaptations of a palisade cell help
- more photosynthesis able to occur
- you can get lots of cells near the top of the leaf for maximum light
function of flower
attract pollinators for reproduction
role of fruit in plant
seed dispersal
function of stem
- transport substances
- support leaves + flowers
function of leaf
photosynthesis
function of roots
- takes up water + minerals from the soil
- anchors plant in the ground
what are the two types of plant tissue
xylem and phloem
what does xylem transport
minerals and water
what is the direction of flow in xylem
one-way (roots -> leaves)
what type of cells are xylem made of
dead cells
describe the structure of a xylem cell
- cells have no end walls so form long hollow tubes
- walls are strengthened with lignin which makes it tough and water-proof
what does phloem transport
sugar
what is the direction of flow in phloem
two-way ( where it’s made => where its needed) translocation
what type of cells are phloem made of
living cells
describe the structure of a phloem cell
- perforated end walls
- companion cells with lots of mitochondria to keep the phloem cells alive and release energy for the movement of sugar
how are leaves adapted for photosynthesis
- broad and flat to give a large SA to absorb sunlight
- thin so carbon dioxide can easily diffuse through to the palisade cells
- conatin chlorophyll to absorb light energy
what tissues does the leaf organ contain
- epidermis
- palisade mesophyll
- spongy mesophyll
- xylem
- phloem
- guard cells
how is epidermal tissue adapted for its function
covers the entire plant, waxy cuticle helps reduce water loss
how is palisade mesophyll tissue adapted for its function
contains lots of cholorplasts which allows photosynthesis to occur at a rapid rate
how is spongy mesophyll tissue adapted for its function
lots of air spaces which allows gases (including O2 and CO2) to diffuse in and out
how is meristem tissue adapted for its function
made of stem cells which can differentiate into many differnet cell types allowing the plant to grow.
what is the function of guard cells
control the opening and closing of the stomata, dependent on the water content of the plant
how are stomata adapted for their function
control of gaseous exchange and water loss from leaf:
* more stomata on the base of the leaf - minimises water loss as this side is cooler and shaded
* have guard cell which control their opening and closing
4 main factors that affect rate of phtotosynthesis
- temperature
- light intensity
- CO2 concentration
- amount of chlorophyll
what factors affect transpiration
- increase in temp.
- increase in wind sped
- increase in humidity
- increase in light intensity
how does transpiration work
- water evaporates from the leaf’s surface via the stomata
- water molecules cohere together - more water is pulled up the xylem in an unbroken column
- more water is taken up from the soil - creating a continuous transpiration stream
how does an increase in temp. affect trasnpiration
causes an increase in tranpiration rate
- higher the temp. the more energy the water particles will have therefore they will move faster and evaporate quicker
how does an increase in wind speed affect transpiration
increase in transpiration rate
- if airflow is poor, water vapour will surround the leaf which would reduce the concentration gradient so less water would evaporate
- high wind speed improves airflow
how does an increase in humidity affect transpiration
decrease in transpiration rate
- water vapour diffuses more rapidly into dry air than into humid air because the conc. gradient is steeper
how does an increase in light intensity affect transpiration
increase in transpiration rate
- if light intensity is high,rate of photosynthesis is higher so stomata open more to let in more CO2 so moe water evaporates
how can a potometer be used to measure transpiration rate
- measure water uptake of a plant
- the more water lost in transpiration, the more water a plant will take up
- measuring the distance the bubble has travelled over a set period of time.
what factors affect number of stomata
- type of plant
- external conditions (light intensity, humidity, co2 conc)
how do guard cells and stomata work
- when the stomata need to open, potassium is pumped into the guard cell by active transport
- this increases the solute concentration and makes water move into the cell by osmosis
- guard cells swell and due to uneven thickening of their cell wall they become more curved
- this opens the stomata
- when the stomata need to close, potassium then water leave the guard cells and they become flaccid (less curved) closing the gap
what is photosynthesis
the process by which plants synthesise glucose using light energy from the sun.
light energy => chemical energy
what type of reaction is photosynthesis
endothermic - needs an input of energy from the environment, the input needed is more than the output
where does photosynthesis take place
within chloroplasts in leaf palisade cells, they contain chlorophyll, a pigment which absorbs light energy
what is transpiration
evaporation of water vapour from the surface of a plant
what is translocation
the movement of dissolved sugars from the leaves to other parts of the plant
state the equations for photosynthesis (word & symbol)
carbon dioxide + water → glucose + oxygen
6CO2 + 6H2O → C6H12O6 + 6O2
how can you show that a plant gives off oxygen in photosynthesis
using a water plant (e.g. elodea) collect gas bubbles produced during photosynthesis. the gas will relight a glowing splint as it contains oxygen
leaf adaptations that maximise rate of photosynthesis
- broad leaves - maximise SA
- thin leaves - short diffusion distance
- chlorophyll present - trap light energy
- veins - transport water to leaves via xylem, remove photosynthesis products via phloem
- air spaces - allow CO2 in and O2 out
- guard cells - control opening of stomata for gaseous exchnage and reduce water loss
what is glucose converted into?
- starch - storage
- cellulose - build or strengthen walls
- nitrates & minerals from the soil (amino acids) - converted to proteins to use as enzymes and for growth and repair
- fats and oils - growth and energy stage
why use starch for storage
- starch can be quickly converted back into glucose for respiration when needed
- it is insoluble so it does not flow out of the cells it is stored in and it does not affect the water conc -> osmosis
how does increase in temperature affect rate of photosynthesis
rate of photosynthesis increases at first as the particles have more kinetic energy. however after a certain point the rate decreases as enzymes have become denatured
how does increase in light intensity affect rate of photosynthesis
rate of photosynthesis increases up to a point. the rate will then stop increasing because there isnt a high enough CO2 conc. or temperature
how does increase in CO2 conc. affect rate of photosynthesis
rate of photosynthesis increases up to a point. rate then stops increasing because there isnt a high enough light intensity or temperature
how does the amount of chlorophyll affect rate of photosynthesis
decreasing the amount of chlorophyll (due to a lack of magnesium) decreases the rate of photosynthesis as chlorophyll is needed to absorb light energy
what is a limiting factor
an environmental factor which can restrict the rate of photosynthesis e.g. light intensity
how can farmers use their knowledge of limiting factors to maximise profits
they can control temperature, light intensity and CO2 conc. to achieve the fastest possible rate of photosynthesis leading to a greater yield.
what equation links light intensity and distance
inverse square law:
light intensity ∝ (1/distance2)
aerobic respiration equations (word & symbol)
C6H12O6 + 6O2 → 6CO2 + 6H2O
glucose + oxygen -> carbon dioxide + water
what is aerobic respiration
exothermic reaction in which glucose reacts with oxygen to release energy which can be used by cells
where does aerobic respiration take place
in the mitochondria
why do organisms require the energy released in respiration
- building larger molecules from smaller ones
- muscle contraction
- maintaining body temperature
- active transport
what is anaerobic respiration
exothermic reaction in which glucose is broken down incompletely to release energy when there is an absence of oxygen
what is the equation for anaerobic respiration
glucose -> lactic acid
why is anaerobic respiration less efficient than aerobic respiration
glucose is not completely broken down so less energy is transferred
why can anaerobic respiration lead to muscle fatigue
lactic acid builds up in muscles preventing efficient contraction
what is an oxygen debt
the amount of oxygen needed to convert lactic acid back to glucose after anaerobic respiration
what is fermentation
a type of anaerobic respiration that occurs in yeast cells
what is the equation for fermentation
glucose -> ethanol + carbon dioxide
why is the fermentation reaction important
it is used in the production of bread and alcoholic drinks
what are the differences between aerobic and anaerobic respiration
- aerobic respiration requires oxygen; anaerobic does not
- aerobic produces CO2 and water; anaerobic produces lactic acid or ethanol + CO2
- aerobic transfers a greater amount of energy
how do muscles store glucose
as glycogen
what changes take place when muscular activity increases in the body?
- heart rate increases and arteries dilate - increases flow of oxygenated blood to the muscles
- breathing rate and depth increases - increases the rate of gas exchange
- stored glycogen is converted back to glucose
how is lactic acid transported away from muscles
blood flow through muslces transports lactic acid to the liver, where it is oxidised back to glucose
what is metabolism
the sum of all reactions that take place in a cell or an organism
how do cell use the energy transferred by respiration
to continuously carry out enzyme-controlled processes which lead to the synthesis of new molecules
give examples of metabolic reactions
- glucose into starch/glycogen/cellulose
- glycerol and fatty acids into lipids
- glucose and nitrate ions into amino acids
- photosynthesis
- respiration
- breakdown of excess proteins into urea
symbol equation for anaerobic respiration in yeast
C6H12O6 - > 2C2H5OH + 2CO2
