B6 - plant structure and function Flashcards
what is the word equation for photosythesis
CO2 + water —-> glucose + oxygen
—-> = light and chlorophyll
how do plants produce biomass
use energy from the sun to produce glucose, some of which is used to make biomass
what is biomass
the mass of a living material
where does photosynthesis occur
in chloroplasts
contain chlorophyll which absorbs light
what sort of reaction is photosynthesis
endothermic
what is an endothermic reaction
energy is absorbed
products have more energy than reactants
what controls opening and closing of the stomata and how
guard cells: by changing shape
- when swollen with water (turgid) stomata opens
- when limp+low on water(flaccid) stomata closes
what is the role of waxy cuticle layer on leaves
allows plants to retain water
preventing too much loss
what is the role of broad flat leaves
large surface area, sunlight can directly enter the leaf, and more is absorbed
what is the role of veins on leaves
transport water and nutrients through the plant
why are leaves adapted to be thin
allows efficient diffusion of co2 and o2 in and out of the plant
what is meant by rate of reaction (of photosynthesis)
how fast or slow photosynthesis occurs
what is a limiting factor
factors that can limit photosynthesis if there isnt enough of it
what are the limiting factors of photosynthesis
- CO2 conc
- light intensity
- temperature
explain the graph for light intensity on rate of photosynthesis
- rate - Y, light intensity - X
- directly proportional to rate (increase together)
- levels off as there is another limiting factor, increasing light intensity no longer has an effect
explain the graph for CO2 conc on rate of photosynthesis
- rate - Y, CO2 conc - X
- directly proportional to rate (increase together)
- levels off as there is another limiting factor, increasing conc no longer has an effect
explain the graph for temperature on rate of photosynthesis
- rate - Y, temp - X
- directly proportional, both increase
- reaches and optimum temperature
- any hotter rate decreases as enzymes denature
why is rate of photosynthesis inversley proportional to distance from a light source
- light intensity decreases the further away from a light source an object is
- lower light intensity means a slower rate of reaction
- greater distance = lower rate
how does water move through the walls of a plant/ enter a root hair cell
osmosis - high to low conc
how does O2 enter root hair cell
diffusion - O2 conc typically greater outside plant than inside
how do minerals enter a root hair cell
active transport - as conc of minerals is usually greater in the root hair cell than outside. (against conc gradient)
what is a concentration gradient
the difference in concentration of something in different areas
why is active transport used to transport mineral ions into root hair cell
minerals always need to be absorbed into a plant no matter where the higher conc is
how are root hair cells adapted to taking in water and mineral ions
- many mitochondria: energy for active transport
- thin cell wall: faster osmosis + diffusion
- large SA: take in optimum water and minerals
- long hair extentions to cell membrane
how does increased airflow (wind) effect rate of transpiration
rate increases as concentration gradient is maintained as the airflow carries water vapour away from the outside of the plant
what are stomata
tiny pores on the surface of a plant allowing CO2 + O2 to diffuse directly in and out of the leaf
what is the function of palisade cells
packed w chloroplasts and close to the surface of the leaf allowing light to reach them efficiently
what is transpiration, and how does it occur
the evaporation and diffusion of water from a plants surface
happens due to a constant transpiration stream down a plant
how does high humidity effect transpiration
decreases rate as the conc of water is higher outside the leaf than inside and diffusion cant occur
how does increased temp effect transpiration
increase rate as there is an increase of water evapourating from the stomata
how to measure the rate of transpiration
total distance/ time taken
what is translocation
the movement of food eg. sucrose up AND down a plant
uses energy from respiration
what is job of phloem
transport food to rest of plant for immediate use or storage
what is xylem
hollow tube cells that transport water up the plant
How is phloem adapted for its function?
- Made up of elongated living cells.
- Cells have sieve tubes that connect them together, have tiny pores so that sucrose can move through
into other cells. - Sieve tube cells have few organelles to allow the efficient transport of substances.
How is xylem adapted to its function?
Hollow tubes made of dead cells strengthened by lignin to maintain structure and allow water and minerals to pass through
what direction does phloem transport
up and down
what direction does xylem transport
up
what is a transpiration stream
the flow of water through a plant, from the roots to the leaves, via the xylem vessels.
