Chapter 7

Front 1

Habitat

Back 1

The place in which an organism lives

Front 2

Biota

Back 2

Life forms

Front 3

Biosphere

Back 3

'layer' of the Earth, including waters, lower atmosphere and soil, which supports life; the sum total of all the Earth's ecosystems

Front 4

Biomes

Back 4

Areas od the Earth linked by a common feature

Front 5

Optimum range

Back 5

Narrow range within the tolerance range an organism has for an aboitic factor, and at which the organism functions best at

Front 6

Physiological stress

Back 6

Stess caused when an organism experiences conditions outside its tolerance range

Front 7

Abiotic

Back 7

Non-living, environmental factors that can affect the organisms chance of survival
Eg. temperature, light intensity etc

Front 8

Biotic

Back 8

Living, environmental factors that can affect the organisms chance of survival
Eg. more of the organisms kind, predators, humans etc

Front 9

Tolerance Range

Back 9

This includes the optimum rnage ad the zone of physiological stress. It is where a species can survive.

Front 10

Zone of Intolerance

Back 10

This is the area outside the tolerance range where species cannot survive

Front 11

Ecosystem

Back 11

Ecosystem= Habitat + community of living things

Front 12

Qualitative

Back 12

descriptions that do not involve measurements

Front 13

Quanitiative

Back 13

measurements that can be quantified - expressed in units

Front 14

Stratification

Back 14

vertical differences in abiotic conditions that give rise to distinctive zones

Front 15

Zonation

Back 15

horizontal differences in abiotic conditions that give rise to distinctive zones

Front 16

Phytohormones

Back 16

plant growth substances

Front 17

Coleoptiles

Back 17

the sheath-like covering of the young growing tips of grasses.

Front 18

Gibberellins

Back 18

Promote cell division and elongation in plant shoots; extend internodes and can raise flower heads (bolting).

Front 19

Cytokinins

Back 19

Stimulate cell division and the middle layer of cells (mesophyll) in leaves. They tend to be concerntarted in the startchy material in seeds (endosperm) and in young fruit.

Front 20

Abscisic acid

Back 20

Generally acts as an inhibitor. It promotes closure of stomata particularily during times of water stress; stimulates dormancy in seeds and buds.

Front 21

Ethylene

Back 21

In gaseous state, it is significant in ripening fruits by stimulating the conversion of starch to sugars, increasing the sweetnes of the fruit. Ethylene also stimulates colour change and softening tissues of ripening fruit as in tomatoes and bananas

Front 22

Photoperiodism

Back 22

refers to the physiological reaction of organisms to the length of day or night

Front 23

Phytochrome

Back 23

a pigment that plants use to detect light (a plant photoreceptor) in the red region of the spectrum

Front 24

Short-day

Back 24

describes plants that flower after a long period of darkness (better described as long-night plants).
Eg. potatoes

Front 25

Long-day

Back 25

describes the plants that require long peroids of daylight before flowering.
Eg. spinach or lettuce

Front 26

Day-neutral

Back 26

Describes plants that flower regardless of the lengths of daylight or darkness.
Eg. tomatoes and cucumbers

Front 27

Vernalisation

Back 27

Some species cannot flower unless expossed to a period of very cold weather before spring growth. They need a "cold snap"

Front 28

Dormancy

Back 28

Some plants shut down some of their activities during unfavouable conditions. Energy level requirments are lowered to a minimum when temperatures are low or water scarce.

Front 29

Taxis
(Responses in plants)

Back 29

movement of a whole organism in response, such as a unicellular alga towards a light source (positive phototaxis) or away from a high concerntration of a particular chemicl in a solution (negative phototaxis)

Front 30

Tropism
(Responses in plants)

Back 30

growth movement in response to an external stimulus in which the direction of the stimulus determines the direction of the response (referred to as a unilateral or unidirectional stimulus)

Front 31

Nastic
(Responses in plants)

Back 31

movement of a plant organ that is not determined by the direction of the stimulus (non-directional), such as the opening and closing of flowers in 'sleep' movements

Front 32

Phototropism
(Tropism)

Back 32

Stimulus: Light

Response-
Positive: shoots grow towards the light
Negative: roots (if responsive) grown away

Front 33

Geotropism
(Tropism)

Back 33

Stimulus: Gravity

Repsonse-
Positive: roots grown downwards
Negative: shoots grow upwards

Front 34

Hydrotropism
(Tropism)

Back 34

Stimulus: Water

Response: Roots grow towards water

Front 35

Thigmotropism
(Tropism)

Back 35

Stimulus: Touch, contact

Response: Stems and tendrils grow around or against points of contact with solid objects such as stems of other plants.

Front 36

Chemotropism
(Tropism)

Back 36

Stimulus: Chemicals

Response-
Positive: pollen tubes of some plants are ttracted to the stigma of the same species, enabling fertilisation. The ovary releases chemicals that produce a positive response.

Front 37

Epiphytes

Back 37

Are aerial plants. They grow on the branches and trunks of other plants, but are not parasitic.They include mosses, lichens, orchids and ferns of many kinds and bromeliads. They gain advantage in competing for light by living high up on rainforest trees. As they have no contact with the soil, their main difficulty is obtaining nutrients and in holding water that comes their way