Chapter 9 Nutrition and Transport in Flowering Plants Flashcards
why does a leaf blade have a large flat surface?
-so that it can obtain the maximum amount of light for photosynthesis
- its thin so that carbon dioxide can rapidly reach the inner cells
what is the upper epidermis made of?
single layer of closely packed cells covered by a waxy and transparent cuticle
why is there a cuticle covering the cells?
to prevent evaporation of water vapour
what’s the difference between palisade and spongy mesophyll in shape
the cells in palisade mesophyll is more elongated while spongy is more irregular
which part of the leaf has the most chloroplast
palisade mesophyll
where is the main site of photosynthesis
palisade mesophyll as it has the more chloroplast
which part of the leaf contains transport tissue (xylem and phleom)
spongy mesophyll
what are the intercellular air spaces for ?
gas exchange and evaporation
what is the function of stomata
it opens in the presence of light, allows carbon dioxide to diffuse in and oxygen to diffuse out
how does carbon dioxide enter the leaf
1.carbon dioxide diffuses in from surrounding air through stomata into the intercellular air spaces
2. it dissolves in the thin film of moisture covering the cells
3. diffuses into the cells
what is the function of xylem
1.transport water and mineral salts from the roots to the leaves
2. provide mechanical support
what are the adaptations of xylem
- long hollow continuous tube without cytoplasm or cross walls-> reduces resistance to water flowing through
- inner walls with lignin (hard substance) -> prevents collapse
what the function of phloem
transport food from leaves to other parts of the plant( translocation)
whats the adaptation of phloem
made of long tubes, with rows of living cells with cross walls separating the cells –> allow rapid flow of food substances
what’s in a vascular bundle?
from the inside,
xylem, cambium, phloem
what’s the word equation of photosynthesis?
carbon dioxide+water —-light and chlorophyll— –> glucose +oxygen
what does alcohol do to the leaf
it removes the green pigment chlorophyll
what does sode lime and potassium hydroxide do
it absorbs co2
what are factors affecting rate of photosynthesis
light intensity, amount of carbon dioxide, temperature
how does light affect rate of photosynthesis?
as light intensity increases, the rate of photosynthesis increases
how does concentration of carbon dioxide affect rate of photosynthesis
as carbon dioxide increases, the rate of photosynthesis increases
how does temperature affect rate of photosynthesis
as temperature increases to the optimum temperature, the rate of photosynthesis increases.
what happens if temperature is above the optimum temperature
the rate of photosynthesis decreases as enzymes would denature
what happens to excess glucose during the day
it is converted to starch
what happens to glucose in darkness
as photosynthesis stops, the glucose that was converted to starch during the day is converted back to glucose by enzymes
what is translocation
the transport of food, sucrose and amino acids in the phleom tissue
why does a tree grow downwards and sideways
downwards: can reach mineral salts and water
sideways: to provide stability for the plant
how does water enter the plant
as the cell has a higher water potential than the next cell, it enters by osmosis
how is the root hair cell adapted?
1.long and narrow extension –> increases surface area to volume ratio –> increases rate of adsorption
2. cell membrane prevents cell sap from leaking out –> lower water potential than soil solution –> water entering the roots by osmosis
what’s is transpiration
the loss of water vapour from the leaves and stems of plant through stomata of leaves
what is transpiration pull
the suction force which pulls water and mineral salts up the plant
how does water move inside the leaf?
- water evaporates from the thin film of moisture surrounding the mesophyll cells, forming water vapour in the intercellular air spaces
- water vapour diffuses through stomata
- the water moves out to replenish the mesophyll cells
- water moves out by osmosis as the water potential in the mesophyll is lower
why is transpiration important
- it draws water and mineral salts from the roots to other parts of plant
- evaporation of water cools the plant, prevent it from being scorched
what are factors affecting the rate of transpiration
HWLT
wind, temperature, light intensity, humidity
how does wind affect rate of transpiration
when there is wind
1. water vapour outside is blown away
2. concentration gradient from water inside and outside is steep
the stronger the wind, steeper the concentration gradient, higher the rate of transpiration
how does temperature affect rate of transpiration?
as temperature rises:
1. rate of evaporation increases
2. concentration gradient inside and outside the leaf steeper
higher the temperature, higher the rate of transpiration
how does light intensity affect rate of transpiration
in bright light:
1. stomata opens and becomes wider
2. more water is lost from leaf
as light intensity increases, rate of transpiration
how does humidity affect rate of transpiration
when more humid
1. concentration gradient between leaf and surrounding air is less steep
as humidity increases, concentration gradient less steeper, lower rate of transpiration
what is wilting
when rate of transpiration exceeds rate of absorption of water, the plant will become flaccid and the plant wilts
what are advantages of wilting
the leaf folds up:
1. surface area exposed to light reduced –> reduce exposure of stomata –> reduce rate of water loss –> cause guard cells to be flaccid –> rate of transpiration is reduced
what is disadvantages of wilting
as stomata closed –> carbon dioxide entering reduced –> decreased rate of photosynthesis
reduces surface area exposed to light –> reduce rate of photosynthesis
