9 Plant Science

Front 1

Transpiration

Back 1

is the loss of water vapour from the leaves and stems of plants.

Front 2

Tissue of the leaf

Back 2

palisade mesophyll, upper Epidermis, xylem, phloem, guard cells, stoma, spongy mesophyll

Front 3

function of the palisade mesophyll

Back 3

- densely packed cylindrical cells with many chloroplasts
- main photosynthetic tissue

Front 4

function of the upper Epidermis

Back 4

- continous layer of cells covered by a thick waxy cuticle
- prevents water loss

Front 5

function of the xylem

Back 5

- transport of water

Front 6

function of the phloem

Back 6

- transport of products of photosynthesis

Front 7

function of the guard cells

Back 7

- control the amount of transpiration

Front 8

function of the Stoma

Back 8

- diffusion of O2 and CO2

Front 9

function of the spongy mesophyll

Back 9

- consists of loosely packed rounded cells with few chloroplasts
- main gas exchange surface

Front 10

abscidic acid

Back 10

causes guard cells to close the stomata, produced when plants are suffering water stress

Front 11

Abiotic factors that have an effect on Transpiration (4)

Back 11

1. Light:
- guard cells close the stomata in darkness
2. Temperature:
- as temperature rises the rate of transpiration rises
3. Humidity:
- the lower the humidity the steeper the concentration Gradient and therefore the faster the rate of Transpiration
4. wind:
- wind blows the saturated air away and therefore increases the rate of transpiration

Front 12

xerophytes

Back 12

plants that are adapted to grow in very dry habitats

Front 13

adaptations of xerophytes

Back 13

- vertical stems to absorb sunlight early and late in the day but not at midday when light is most intense
- CAM physiology which involves opening stomata during the cool nights instead of in the intense heat of the day
- spines instead of leaves to reduce the surface area for Transpiration
- very tick waxycuticle covering the stem

Front 14

increase surface area for absorption by ...

Back 14

branching roots and the growth of root hairs

Front 15

plants absorb ... by ... because...

Back 15

1. potassium, Phosphate, nitrate and other mineral ions from the soil
2. active transport
3. the concentration inside the roots is higher than in the soil

Front 16

Three ways in which ions can move

Back 16

- diffusion of mineral Ions
- mass flow of water carrying ions, when water drains through the soil
- into fungal hyphae, that grow around the plant roots in a mutualistic relationship, and the form the hyphae to the roots

Front 17

structure of the stem

Back 17

Front 18

support of the stem (3)

Back 18

- cells absorb water and high pressure develops inside the cell. This is cell turgor and it males the cell almost rigid.
- some cells develop thickened cellulose walls, which strengthen the plant
- cell walls in xylem tissue are both thickened and lignified making them very strong

Front 19

structure of xylem vessel

Back 19

- no plams a membranes so water can move in and out freely
- lumen of the xylem vessel is filled with sap
- helical or ring-shaped thickenings of the cellulose wall --> support

Front 20

transpiration stream

Back 20

when transpiration is occuring, water moves upwards from the roots to the leaves

Front 21

Evaporation

Back 21

heat from the environment provides energy for Evaporation of water from the cell walls of the spongy mesophyll in the leaves

Front 22

transpiration pull

Back 22

low pressure of suction is created inside xylem Kessels when water is pulled out

Front 23

cohesion and adhesion of water prevents ..

Back 23

the columns of water from breaking

Front 24

active translocation

Back 24

transport of sugars and amino acids by the phloem

Front 25

sources

Back 25

where sugars and amino acids are loaded in the phloem

Front 26

sinks

Back 26

where sugars and amino acids are unloaded from the phloem

Front 27

female gametes are contained in ..

Back 27

ovales in the ovaries of the flower

Front 28

male gametes are contained in ..

Back 28

pollen grains produced by the anthers

Front 29

zygote

Back 29

formed by the fusion of a male gamete with a female gamete inside the ovule. This process is called fertilization.

Front 30

pollination

Back 30

pollination is the Transfer of Pollen from an Panther to a stigma

Front 31

most plants use either ... or ... for pollination

Back 31

wind, animals

Front 32

seed disperal

Back 32

function of the fruit which are ovaries containing fertilized ovules

Front 33

structure of a flower

Back 33

Front 34

external conditions for seed germination

Back 34

1. water must be available for rehydration
2. oxygen must be available for Aerobic cell respiration
3. suitable temperatures are needed, enzyme activity

Front 35

structure of a seed

Back 35

Front 36

metabolic events during germination

Back 36

1. absorption of water and rehydration of living cells in the seed
2. plant growth hormone calles gibberellin is produced by the cotyledons of the seed
3. stimulates the production of amylas which catalyzes the digestion og starch from the food stores of the seed
4. maltose is transported from the food stores to the growth regions of the seedling
5. maltose is converted into Glucose, which is either used as a source of enegry for cell respiration or to Synthesis cellulose

Front 37

differences between mono- and dicotyledons

Back 37

M: leaf veins run parallel to each other
D: leaf Weins form a net-like Pattern

M: vascular bundles are spread through the stem randomly
D: vascular bundles are in a ring near the outside of the stem

M. stamens and other organs in the flower are in multiples of 3
D: stamens and othe floral organs are in multiples of 4

M: unbranched roots
D: branched roots

Front 38

Bulbs

Back 38

-food storage

Front 39

stem tubers

Back 39

- food storage

Front 40

storage roots

Back 40

eg carrots

Front 41

tendrils

Back 41

- allow the plant to attach and grow upwards

Front 42

meristems

Back 42

regions where plants continue to divide and grow

Front 43

apical meristems

Back 43

meristems at the tip of the root and stems to elongate

Front 44

lateral meristems

Back 44

cambium in the vascular bundles, makes roots and stem thicker

Front 45

Is the night or the day length significant for short- day plants and long-day plants?

Back 45

night

Front 46

auxin

Back 46

plant Hormone, which acts as a growth Promoter

Front 47

phototrophism

Back 47

directional growth in response to the source of light (controlled by auxin)

Front 48

auxin efflux carriers

Back 48

pumps in the plasma membranes --> redistribute auxin in a tissue

Front 49

auxin receptor

Back 49

when auxin binds to it, transcription of specific genes is promoted

Front 50

phytochrome

Back 50

Pigment in leaves which measured the length of dark periods

Front 51

2 forms of phytochrome

Back 51

1. Pr:
inactive form, absorbs red light
when it absorbs red light it is quickly converted into Pfr
2. Pfr:
active form, absorbs far red light
when it absorbs far red light it is rapidly converted to Pr

In daylight (more red light than far red light): Pfr present
In darkness: Pfr converts slowly into Pr