Unit 2 Bio- Environmental factors and adaptations

Question 1

Define hydrophyte.

Answer 1

A hydrophyte is an aquatic vascular plant that has few stomata and large intercellular air spaces to provide buoyancy and retain gases.

Adaptations: (partially) submerged, little or no cuticle, air spaces for gases and buoyancy.

Question 3

What is an adaptation?

Answer 3

An adaptation is an inherited characteristic that increases the likelihood of survival and reproduction of an organism.

Can be structural, behavioural or physiological.

Question 4

Define environment

Answer 4

The environment of an organism includes both the living (biotic) and non-living (abiotic) surroundings of an organism. The environment provides an organism with it’s essential requirements.

Question 5

Define adapt.

Answer 5

To change behaviour or physiology to cope with changes in the internal or external environment. Such changes are short term and are not passed into offspring.

Question 6

What is the difference between biotic and abiotic factors?

Answer 6

Abiotic: non-living; physical surroundingsBiotic: living; other organisms with which an organism interacts

Question 7

Define cambium.

Answer 7

A region of rapidly dividing cells that produces secondary growth in woody plants.The cambium is a plant tissue that produces regenerative growth of bark and woody tissues and is necessary for stem survival.

Question 8

Explain circulatory adjustments.

Answer 8

Animals in hot, arid environments are often under abiotic stress in relation to body temperature. Temperature regulation in desert animals can be assisted by circulatory adjustments. These adjustments alter the flow of blood though the skin and thereby alter the rate of heat exchange.

Question 9

What is a cuticle?

Answer 9

An outer waxy layer, impermeable to water.

Question 10

Explain distribution.

Answer 10

The area in which a species of organisms lives, influenced by their tolerance range.

Question 11

What are epicormic buds?

Answer 11

(epi= on, corm= stem). Epicormic buds, which lie under the bark of stems, allow sprouting and regrowth after damage to the plant, like fire.

Question 12

Explain evaporative cooling.

Answer 12

A system used to help regulate temperature for animals in hot climates. It occurs through sweating or panting (although this is a problem for desert animals because of the associated loss of water).

Question 13

What is a halophyte?

Answer 13

A halophyte is a plant adapted to a saline (salty) environment. Halophytes are able to regulate water loss and control salt accumulation in leaves.

Adaptations: water storage in specialised tissues, air spaces in roots and stems, salt glands, reduced leaves.

Question 14

Explain gases in terms of abiotic and biotic factors.

Answer 14

Gas is a common abiotic factor, particularly in water. pH is a useful indicator of the CO2 concentration. Moderate increases in CO2 can stimulate higher photosynthetic activity in aquatic plants, but too much CO2 can be very limiting for aquatic animals. Oxygen is another gas factor in water, and is often limiting to he organism because water contains much less oxygen than air.

Question 15

What is humus?

Answer 15

Organic matter formed from the breakdown of dead plants and animals; makes a dark layer in topsoil.

Question 16

What is a lignotuber?

Answer 16

A lignotuber is a swelling at he base of a stem that is the source of dormant buds. Lignotubers are present even in young seedlings of many eucalypts and are best developed in mallee species. Lignotubers, like rhizomes and root suckers, allow rapid regeneration from subterranean buds when all aerial parts of a plant have died.

Question 17

What is a limiting factor?

Answer 17

An environmental requirement that is in limited supply and thus may potentially affect the survival and reproduction of an organism.

Question 18

Explain hibernation.

Answer 18

Hibernation involves a controlled lowering of body temperature (long-term torpor) as a mean of reducing energy expenditure at a time when metabolic demands would otherwise be very high.

Question 19

What is metabolic heat?

Answer 19

Internal heat generated from metabolism (the physical and chemical process of an organism).Eg, Muscle activity. Metabolic heat is an important factor in maintaining a high body temperature in mammals and birds.

Question 20

Explain pH in terms of biotic and abiotic factors.

Answer 20

pH is an abiotic factor, especially associated with water. It is a measure of it’s acidity or alkalinity. it is determined largely by the amount of dissolved CO2, which forms carbonic acid in water. Many organisms tolerate a wide range of pH conditions, and thus pH is not a very limiting factor, but can be used to determine other factors that are. For example,. acid soils are often nutrient deficient.

Question 21

Explain the term ‘mycorrhiza’.

Answer 21

Most plants have a symbiotic relationship with soil-inhabiting fungi. The thread-like hyphae (minute, thread-like structures that make up fungi) of the fungi are closely associated with the outer layer of the root. The hyphae also extend into the soil, absorbing mineral nutrients such as phosphorous. This relationship is called a mycorrhiza.

Question 22

What are pneumatophores?

Answer 22

Pneumatophores are a type of specialised root, found in plants like mangroves. They form part of an aerial root system to maximise oxygen uptake when the tide is low, by increasing the surface area exposed to the oxygen-rich air. They also play a role in stabilising the plant in the soft muddy surroundings.

Question 23

What are proteoid roots?

Answer 23

Dense clusters of hairy roots near the soil surface.

Question 24

Explain salinity in terms of biotic and abiotic factors.

Answer 24

Salinity is an abiotic factor, especially of water. In marine environments, organisms live in salty water. In shallow pools, the sun causes the water to evaporate, leaving behind a higher salt concentration

Question 25

What is a tolerance range?

Answer 25

The range of conditions- for example, temperature- than an organism an survive.

Question 26

Define torpor.

Answer 26

Torpor is when vertebrate animals allow their body temperature to drop and they become inactive or dormant for a period of time.

Question 27

What is a xerophyte?

Answer 27

A xerophyte is a plant that is adapted to arid conditions. Xerophytes include succulents (fleshy plants) and sclerophylls (hard-leaved) plants.

Adaptations: thick cuticle, distribution of stomata, sunken stomata, low SA.

Question 28

Define habitat.

Answer 28

Place where an organism lives.

Question 29

Define ecosystem.

Answer 29

A self-sustaining unit made up of organisms (a community) interacting with and within a habitat (interaction between living and non-living components).

Ecosystem= habitat+ community of living things

Question 30

What is a microhabitat?

Answer 30

Small regions within a habitat which may have environmental conditions that differ from those in the larger habitat. They support their own micro-community in a micro-ecosystem.

Question 31

Explain the term ‘mesophyte’.

Answer 31

Plants with adequate water.
Adaptations include: guttation, leaf shedding, perennials die down and survive as underground organs, annuals survive as dormant seeds.

Question 32

What are succulents?

Answer 32

Water-retaining plants adapted to arid climates or soil conditions. They store water in their leaves, stems and also in their roots.

Question 33

What are geophytes?

Answer 33

Plants that are able to survive unfavourable periods by dying back to underground storage organs such as tuberous roots, bulbs and rhizomes. They may be regarded as succulents.

Question 34

What are epiphytes?

Answer 34

Aerial plants that grow on branches and trunks of other plants (e.g. mosses and lichens). They are able to gain light easily because of their high position, but this position also means they can have difficulty obtaining nutrients because they do not touch the soil.