IB Biology HL Topic 9
Some revision cards for AHL Topic 9
Terms in this set (131)
Leaf veins that form a net-like pattern, vascular bundles in a ring near the outside of the stem, stamens and other floral organs in multiples of 4/5, roots branch off from other roots; roses or violets
Leaf veins run parallel to each other, vascular bundles spread randomly through the stem, stamens and other floral organs in multiples of 3, unbranched roots grow from stems; lilies or orchids
Vascular tissue (plants)
Made up of xylem and phloem, it transports fluid and nutrients internally
Support for and allow elevation of leaves, flowers and fruits, transport of fluids between roots and shoots in the xylem/phloem, storage of nutrients and production of new living tissue
Main photosynthetic tissue, allows transpiration and stores various food material
Primary plant stem cells found at the tips of stems and roots, it is responsible for the growth of the root and shoot meristem which also produces new leaves and flowers
Consists of cambium in the vascular bundles and is responsible for making roots and stems thicker
Plant hormone which acts as a growth promoter it secretes H+ ions into cell walls which loosens connections between cellulose fibres and allows cell expansion.
Growth towards the light, auxin is distributed to shoots on the darker side, causing it to bend towards the light
Increase surface area for water and mineral ion absorption from the soil
Mass flow of water (apoplastic)
Transport of water through free spaces between cell walls
Diffusion through the cytoplasm of cells via plasmodesmata
Organic polymer deposited in cell walls making them rigid and woody
Osmosis between vacuoles, driven by osmotic gradient pressure
Long, dead, tubular structures containing water and dissolved mineral ions
Lines of living cells containing water with sucrose and other dissolved biochemicals, also has pores between cells
When water moves upwards from the roots to the leaves
When low pressure or suction is created inside the xylem vessels when water is pulled out
Hydrogen bonding between water molecules allow for the formation of water columns
Water molecules stick to the wall of the vessel, particularly important when sap starts to rise
Heat from the environment provides energy for this, water from the cell walls of spongy mesophyll cells in the leaf is removed and as it is pulled out creates a low pressure in the xylem vessels
Pores that allows for carbon dioxide for photosynthesis to diffuse in and oxygen to diffuse out
Pair of cells that can open or close the stoma and thus control the amount of transpiration
Desert plants that are adapted to reduce transpiration
Translocation of sugars
Energy is required for this active transport, sugars and amino acids are loaded into the phloem in the sources and are transported to the sinks
Transfer of pollen from an anther to a stigma
When female gametes in the ovules in the ovaries of the flower and male gametes in the pollen grains fuse to form a zygote
When fertilized ovules develop into seeds and are moved away from the parental plant before germination, through fruits, winds, water and animals
Process whereby seeds or spores sprout and begin to grow to form an embryonic plant. Begins with water absorption thus allowing cells to become metabolically active, the hormone gibberellin stimulates the production of amylase which hydrolyses carbohydrates into maltose or glucose which can be used for cell respiration
Pigment that measure the length of periods of dark and exists in two forms Pr and Pfr
Spatial - Enhances carbon dioxide fixtures during the day by having different chloroplast cells that carry out photolysis and carbon fixation
Temporal - Retains carbon dioxide in the form of maltic acid during the night for use in the day when the stomata are closed
Organic acid that is used to store carbon dioxide during the night and is released during the day to allow photosynthesis when the stomata are closed
Auxin efflux carriers
Pumps in the plasma membrane that are distributed unevenly and thus can redistribute auxin in a tissue, when auxin binds to a receptor the transcription of specific genes is promoted and the cell grows
Terrestrial plant support
Turgid cells that are rigid because of their high pressure, cells with thickened cellulose cell walls and xylem tissue which has cell walls impregnated with lignin, making it woody and hard
Modified shoots that consist of swollen leaf bases attached to a short stem, usually used for food storage; onions and garlics
Swollen underground stem that has a number of reduced scale leaves, usually stored in tubers as starch and protein; potatoes
Swollen roots that are used for food store and have vascular tissue in the centre; carrots and turnips
Modified leaves that are narrow outgrowths from the leaves, they rotate through the air until they touch a solid support to which they attach, allows the plant to climb upwards; sweat pea
Factors needed for seed germination
Water for rehydration of the seed, oxygen for aerobic cell respiration and suitable temperatures for stimulation of enzymes, some seeds remain dormant if temperatures are above or below particular levels
Plant growth hormone that is produced in the cotyledons of the seed and stimulates the production of amylase
Cell connectors which travel through cell walls of plants
Thick waxy cuticle which forms a single outer layer of cells
Thinner waxy cuticle with guard cells and stomata in between
Tightly packed cells in the upper half of the leaf containing many chloroplasts
Loosely packed cells in the lower half of the leaf with large air spaces between them and fewer chloroplasts inside them
Absorbs red light and is an inactive form of phytochrome - most common in daylight
Phytochrome far red
Absorbs far red light and is an active form of phytocrhome - most common in darkness
Plant hormone that causes guard cells to close the stomata
Abiotic factors affecting rate of transpiration
Light: guard cells close stomata in darkness thus rate of transpiration is higher in daylight. Temp.: heat is needed for evaporation of water thus as temperature rises so does the rate of transpiration. Humidity: air spaces between the leaf and outside are nearly always saturated thus the lower the humidity the faster the rate of transpiration. Wind: pockets of air saturated with water vapour form near stomata in still air which reduces the rate of transpiration thus higher winds increase the rate of transpiration
Xerophyte adaptations to reduce transpiration
Thick waxy cuticle to retain moisture. Spines instead of leaves to reduce surface area for transpiration. Rolled leaves that act as channels to drain rainwater to stems. Deep/penetrating roots to capture water
At the base of the flower bud, it covers the flower structure
Surround the male and female flower parts and are there to attract animal pollinators
Surface on which pollen lands and where the pollen tube grows down to the ovary
Connects the stigma and the ovary
Contains the ovules, female reproductive organ, with single egg nuclei
Supports the anther which contains the pollen
Part of the stamen that contains the pollen
Male fertilizing organ, it typically contains an anther and a filament
part of vascular bundle that are responsible for the transports water throughout the plant
- no membrane or organelles are present.
are present allowing water to leave the xylem to cells.
is laid down in rings around the cellulose cell wall. this adds strength (to resist pressure to the xylem)
is filled with sap (water + minerals).
roots anchor the plants in the ground, and absorb minerals (by active transport) and water (osmosis)
roots provide a large surface area due to branching and root hairs (extension of cells)
Absorption of minerals (roots)
-there is usually a higher concentration of minerals within root cells than in the soil.
- root cells use active transport to move minerals from the soil into the root cells.
-there are lots of mitochondria in the root cells to produce ATP for active transport.
- specific protein pumps are present in the plasma membrane of root cells, which actively transport the minerals into the cytoplasm.
Absorption of water
-there is a high concentration of minerals in the cytoplasm of root cells due to active transport
- water moves from the low solute concentration in the soil, through plasma membranes of root cells to the high solute concentration in the root cells's cytoplasm, by osmosis.
- the water (and minerals) moves to the root xylem.
the loss of water from leaves and other organs of the plant
in the xylem
pores at the bottom surface of leaves which allow water to vaporise out of the leaf
The process of transpiration
1) water evaporates from cells within the leaf. the water vapour diffuses out of the lead through stomata.
2) the leaf cells replace the water lost by taking water from the xylem. this reduces the water pressure in the xylem (creating a partial vacuum).
3) water is "pulled" up along the xylem from high pressure in the roots. This is known as transpiration pull.
4) the flow of water in the xylem ( transpiration stream( continues to flow because:
a) water is cohesive (water is a polar molecule which forms hydrogen bonds)
b) water adheres to the cellulose walls of the xylem.
c) the lignified xylem walls are able to withstand pressure.
Abiotic factors affecting transpiration
1) Temperature: as temp increases, the water particles gain kinetic energy and diffuse faster.
2) Humidity (concentration of water in the air): If humidity is low, the water diffuses quickly out of the leaf. If humidity is high, water diffuses slower.
3) Wind: increasing wind usually increases the rate of transpiration.
are plants that have been adapted to tolerate dry conditions (eg. cacti)
- water storage tissue
- the leaves are modified into needles, decreasing surface area for transpiration
- reduces number of stomata
- vertical stems to allow them to absorb maximum sunlight during morning and evening.
- thick waxy cuticles to prevent evaporation of water.
- CAM physiology: a version of photosynthesis where the stomata open at night (to get CO2) but stay closed during the day.
are plants adapted to survive in saline (high salt) conditions.
- they maintain a high salt concentration within a vacuole (known as tonoplast) because high salt in the cytoplasm interferes with metabolism.
- high concentration of other solutes (eg. sucrose) are maintained within the cytoplasm of root cells
- remove excess salt by active transport in the root cells, or by storing salt in special leaves and then shredding them.
- also have many xerophyte adaptations to prevent water loss.
part of vascular bundle that transports the products of photosynthesis throughout the plant
- sieve tubes
- sieve plates
- companion cells
organic compounds (eg sugars + amino acids- are transported in plants from sources to sinks through the phloem.
between the sieve tube cells, which makes it easier for fluids to flow through the phloem
narrow companion cells and sieve tubes.
- maintain the sieve tubes
- have many mitochondria to produce ATP for active transport of organic compounds into sieve tubes.
can be photosynthesising leaves, or storage organs (such as roots) releasing their store of nutrients.
can be storage organs where nutrients are stored, growing leaves, flower, fruit.
- form a column of cells
- have a plasma membrane so that sugar concetration can be controlled.
- does not have a nucleus and not many organelles, so that fluid can flow easily.
Process of translocation
1) sucrose is produced in the leave (a source) by photosynthesis. The sucrose is actively transported into sieve tubes by companion cells.
2) water from the xylem moves into the phloem by osmosis (due to the high sucrose concentration, creating high pressure)
3) the water moving into the phloem;s sieve tubes pushes the water (containing sucrose) towards the sink.
This occurs de to water being incompressible.
4)the fluid in the sieve tubes is pushed towards the sink.
5) the sucrose is then actively transported from the sieve tube into the source cells (eg. storage cells in the root)
6) the sucrose can be used for growth, converted to starch for storage, or respiration.
directional growth or movement of a plant towards or away from stimulus
Directional growth of a plant towards or away from light.
plant hormone that promotes growth in the shoot of plants.
auxin is produced by the shoot tips.
Process of photo tropism
1) light is detected by pigments found in plants including phototropins.
When these detect differences in (blue) light in the short tip, they trigger the movement of auxin by active transport.
2) Auxin efflux pumps are located in the plasma membrane of cells in the shoot. The auxin efflux pumps are used to actively transport auxin through cell from the light side of a plant to the shaded side.
NOTE: auxin efflux pumps are moved to ensure that auxin is moved towards the shaded side
3) Auxin receptors (proteins) are found within the plasma membrane of cells. Auxin binds to the receptor.
This causes changes within the cell that causes certain growth genes to be expressed.
This results in the release of H+ into the cell walls. This loosens connections between cellulose, allowing the cells to grow.
- tissue in a plant consisting of undifferentiated cells which can differentiate into other plant cells, and undergo mitosis and cell division.
- responsible for growth of a plant
- tissue in a plant responsible for growth in width
- found between xylem and phloem
Micropropagation of plants
produces many genetically identical plants in a short period of time.
the production of many genetically identical plants in a short period of time.
1) tissue from stock plants with desirable characteristics are obtained and sterilised before being cut into many small pieces. NOTE: must contain meristem in tissue
2) the explant is transferred to a growth medium which contains hormones. The explant develops roots and stems.
3) the plant is transferred to the soil
Micropropagation is used for rapid bulking:
- production of virus free varieties of plants
- rapid production of new varieties of traits which are desired by the market
- rapid production of large numbers of endangered species such as orchids.
female reproductive organs of an angiosperm
male reproductive organs of a plant that produces pollen
stalk of stamen that holds up the anther
attract pollinators for pollination with colours
produces the pollen grains, which house male gametes, or sex cells, necessary for reproduction.
protect the developing flower while in the bud
structure of carpel that holds up the stigma
base of carpel in which the female sex cells develop
sticky top of carpel on which pollen lands
- the transfer of pollen grains from the male anther to the female stigma.
- the pollen contains sperm
- often facilitated by animals, wind or water movement.
- fusion of the male gamete(sperm) with the female gamete(egg) to form a zygote.
- In plants, pollen lands on the stigma. It germinates and grows down through the style to the ovary.
- the zygote develops into a seed.
- is the movement of seeds away from the parent plant
- reduces competition to ensure that the new plant does not compete for resources with the parent plant
Germination of seeds
all seeds require oxygen (for aerobic respiration), water (most metabolic reactions occur in water) and a suitable temperature (required for the enzyme involved in germination)
some seeds require other conditions such as light, fire, frost before they will germinate.
Process of seed germination:
1) water enters the micropyle
2) the seeds swells up and bursts, this promotes the release of the hormone giborrelin
3) the hormone stimulates the release of the enzyme amylase which catalyses the breakdown of starch stored within the seed, into maltose.
4) the maltose breaks down into glucose to produce ATP and to produce a cellulose cell wall.
Absorption of mineral ions will result in roots cells being in a ____ environment, which will result in the ___ of water.
out of, into
The pumping of hydrogen ions ___ root cells creates a concentration gradient. As ions move back down the gradient, they lose energy which can be used to pump minerals ___ the root cells.
sink cells, xylem
Once the sap in phloem vessels arrives at a sink, the solutes will diffuse into ___ and water will diffuse into ___
up from the roots, all directions
Within a plant, fluid in xylem tissue moves ___, and the fluid in phloem tissue moves ___
living, actively transport sucrose across its membrane
The sieve elements in phloem tissue are considered ___ because they ____.
simple diffusion through the holes in the sieve plate
Once sucrose has entered the network of phloem vessels, it will move toward a sink by:
active transport powered by a flow of hydrogen ions
Sucrose will be loaded into phloem tissue using:
an end plate containing holes
Which structural feature below helps a phloem cell perform its function?
a high concentration of sucrose draws water into the phloem
What causes hydrostatic pressure to increase in phloem tissue?
sucrose and amino acids
Which are transported by phloem tissue?
During micropropagation, an apical meristem is removed from a plant and grown in a nutrient agar. When exposed to higher ratio of auxin to cytokinins (e.g. 20:1) the meristem will produce ____. When exposed to lower ratio of auxins to cytokinin (e.g. 10:1), the meristem will produce ____.
phototropins absorb sunlight
phototropins shape is transformed and binds to a receptor protein
protein complex binds to promoter site on DNA transcription and translation of PIN3 protein
PIN3 embedded in the plant's cell membrane
active transport of the hormone auxin out of the cell
Order the sequence of events below that describe how sunlight is involved in transporting auxin to the sunny side of a plant
In the presence of sunlight, auxin is moved to the ___ side of a stem where it will ___ cell elongation.
terminal and lateral buds, height
Apical meristem consist of _______________ and is responsible for an increase in the ____ of a plant
auxin enters a cell
auxin binds to a receptor protein
protein complex binds to a promoter region on DNA
transcription and translation of cellulase
cellulase loosens fibers in the cell wall
cell wall stretches with increased turgor pressure
Order the following steps that describe how auxin is involved in promoting cell elongation.
auxin induced pumping of hydrogen ions through cell membrane to the cell wall
auxin induced production of cellulase
increased turgor pressure
Which are involved in the elongation of a cell in the stem during plant phototropism?
If a seedling is turned on its side, auxins will sink to the bottom of cells. In root tissue, auxins will ___ cell elongation, and in stem tissue it will ___ cell elongation.
In germination, the hydration of a seed will result in cells producing the hormone ___. This hormone will stimulate the production of ___.
certain hormones will alter the gene expression in apical meristem
Best describes the cause of flower production?
In sunlight, Red Phytochrome (Pr) will ____ be converted into Far-red Phytochrome (Pfr). At night, Pfr will ___ break back down into Pr
In a short-day plant, Far-red Phytochrome (Pfr) will act as a flower _____, and in long-day plants Pfr will act as a flower ____.
Far-red Phytochrome; Red Phytochrome
In the long days of summer, leaves will accumulate ___, and during the shorter days of spring or fall, they will accumulate ___.
In germination, the enzymatic breakdown of starch in the cotyledon is essential for the process of ___ to occur.
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