B6 Plant Structures and their Functions Flashcards
Define
biomass.
the mass of living biological organisms in a given area or ecosystem at a given time
What is the order of labels in a food chain?
producer - primary consumer - secondary consumer - tertiary consumer - quaternary consumer
What is the equation for
photosynthesis?
… carbon dioxide + water …
…………………….|…………………….
light (energy) | chlorophyll
…………………….↓…………………….
…….. glucose + oxygen ………
(6CO2 + 6H2O -> C6H12O6 + 6O2)
What are plants’
uses of glucose?
- to make cellulose, the main structural material in cell walls
- to store energy as starch or sucrose
- to make fats & oils
- for growth, repair and replacement of damaged parts
- as an immediate energy source for respiration
What is the
structure of a leaf?
(from top to bottom)
waxy cuticle
upper epidermis
pallisade mesophyll cells
spongy mesophyll cells
lower epidermis/guard cells
What are
stomata?
(and what do they do?)
holes/pores in the underside of a leaf that allow for gas exchange
What is
phloem?
(and what does it do?)
a tissue which carries sugars from a leaf
What are
guard cells?
(and what do they do?)
cells at the bottom of a leaf which control the size of the stomata
(to control water loss)
What are
pallisade cells?
(and what do they do?)
cells which contain many chloroplasts and carry out most of the photosynthesis in a leaf
What is
xylem?
(and what does it do?)
the tissue which carries water to a leaf
What are
spongy mesophyll?
cells with air pockets which carry out a bit of photosynthesis
What is the
waxy cuticle?
(and what does it do?)
a waterproof layer at the top of leaves which stops water from evaporating from the cells
What conditions limit photosynthesis?
- carbon dioxide levels
- light intensity
- temperature
What is the inverse square law?
(calculating new light intensity)
new light intensity = original light intensity x (original distance)^2 / (new distance)^2
(light intensity is measured in lux)
What are roots used for?
- extracting water
- extracting mineral ions
- anchorage
Describe a
turgid plant cell.
- full of water
- gives support
- vacuole is filling all of the space and pushing against the cell wall
Describe a
flaccid plant cell.
- starting to lose water
- gives some support
- vacuole is much smaller and taking up less space
Describe a
plasmolysed plant cell.
- very dehydrated cell
- gives little support
- cell membrane + cytoplasm far from cell wall in most places
Define
osmosis.
the net movement of water across a partially permeable membrane from a high water potential to a low water potential
How are root hair cells adapted to absorb water and mineral ions?
- large surface area
- thin cell walls
- large permanent vacuole containing sugars
- many mitchondria which release energy for active transport
What are the characteristics of
xylem?
- transports water and minerals
- no end walls between cells
- one-way only
- outer cells are not living
- movement is upwards
- carries out transpiration
What are the characteristics of
phloem?
- transports organic molecules
- end walls between cells
- two-way movement
- cells are living but need support
- carries out translocation
What is the
structure of xylem?
- composed of dead cells
- no top and bottom cell walls
- cell walls are thickened and contain rings of lignin
- forms continuous xylem vessels which are rigid
- prevents bursting or collapsing under pressure
- supports the plant
- tiny pores called pits connect adjacent xylem vessels
What is the
transpiration stream?
the movement of water upwards through the plant xylem
What is
transpiration?
the flow of water into a root, up the stem and then out of the leaves via evaporation then diffusion
What is
water’s journey to the xylem?
- Water enters the root hairs by osmosis.
- Water passes across the root, from cell to cell by osmosis. It also seeps between the cells.
- Water is drawn up the xylem vessels because transpiration is constantly removing water from the top of them.
What factors change the rate of transpiration?
- temperature
- humidity
- wind
- light intensity
