question

Xylem

answer

part of vascular bundle that is responsible for the transports water throughout the plant - no membrane or organelles are present.

question

Pores

answer

are present allowing water to leave the xylem to cells.

question

Lignen

answer

is laid down in rings around the cellulose cell wall. this adds strength (to resist pressure to the xylem)

question

Lumen

answer

is filled with sap (water + minerals).

question

Roots

answer

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)

question

Absorption of minerals (roots)

answer

-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.

question

Absorption of water

answer

-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.

question

(Evapo) Transpiration

answer

the loss of water from leaves and other organs of the plant in the xylem

question

Stomata

answer

pores at the bottom surface of leaves which allow water to vaporise out of the leaf

question

The process of transpiration

answer

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.

question

Abiotic factors affecting transpiration

answer

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.

question

Xerophytes

answer

are plants that have been adapted to tolerate dry conditions (eg. cacti)

question

Xerophyte adaptations

answer

- 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.

question

Halophytes

answer

are plants adapted to survive in saline (high salt) conditions.

question

Phloem

answer

part of vascular bundle that transports the products of photosynthesis throughout the plant

question

Phloem structure

answer

photo ! - sieve tubes - sieve plates - companion cells - plasmodesmata

question

Translocation

answer

organic compounds (eg sugars + amino acids- are transported in plants from sources to sinks through the phloem.

question

Sieve plates

answer

between the sieve tube cells, which makes it easier for fluids to flow through the phloem

question

Plasmodesmata

answer

narrow companion cells and sieve tubes.

question

Companion cells

answer

- maintain the sieve tubes - have many mitochondria to produce ATP for active transport of organic compounds into sieve tubes.

question

Sources

answer

can be photosynthesising leaves, or storage organs (such as roots) releasing their store of nutrients.

question

Sink

answer

can be storage organs where nutrients are stored, growing leaves, flower, fruit.

question

Sieve tubes

answer

- 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.

question

Process of translocation

answer

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.

question

Tropism

answer

directional growth or movement of a plant towards or away from stimulus

question

Phototropism

answer

Directional growth of a plant towards or away from light.

question

Auxin

answer

plant hormone that promotes growth in the shoot of plants. auxin is produced by the shoot tips.

question

Process of photo tropism

answer

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.

question

Meristem

answer

- 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

question

Lateral meristem

answer

- tissue in a plant responsible for growth in width - found between xylem and phloem

question

Micropropagation of plants

answer

produces many genetically identical plants in a short period of time.

question

Flower structure

answer

Female [carpel] - anther - filament - petals Male [stamen] - stigma - style - ovary - sepals

question

carpel

answer

female reproductive organs of an angiosperm

question

anther

answer

male reproductive organs of a plant that produces pollen

question

filament

answer

stalk of stamen that holds up the anther

question

petals

answer

attract pollinators for pollination with colours

question

stamen

answer

???

question

sepal

answer

protect the developing flower while in the bud

question

style

answer

structure of carpel that holds up the stigma

question

ovary

answer

base of carpel in which the female sex cells develop

question

stigma

answer

sticky top of carpel on which pollen lands

question

Pollination

answer

- 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.

question

Fertilisation

answer

- 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.

question

Seed dispersal

answer

when a seed, formed from a fertilised ovule, is moved away from the parental plant to reduce competition for resources.

question

Germination of seeds

answer

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.

IB Biology Topic 9: Plant Biology HL

Unlock all answers in this set

Haven't found what you were looking for?

Search for samples, answers to your questions and flashcards