TERM 4 - IMMUNE RESPONSE AND ECOLOGY- PART 1

Question 1

Define:
interdependence
Parasitism
Commensalism

Answer 1

• how all species are connected in a food web
• where one organism benefits from relationship and other one is harmed
  -one organism benefits while other one is unaffected

Question 2

farmers find that adding fertilisers to loam soils increases crop yield while adding them to sandy soil does little. Explain why?

Answer 2

Sandy soil is not good for agriculture because, it cannot hold the water and it has big soil particles. However, loam soil holds plenty of moisture but also drains well so that sufficient air can reach the roots.

Question 3

Explain how seasonal changes in abiotic factors can alter the rate of birth, death, immigration and emigration?

Answer 3

modifies water quality and quantity, differentially affecting fish survival and, consequently, modifying species richness and abundance. Abiotic limiting factors restrict the growth of populations. They help determine the types and numbers of organisms able to exist within an environment.

Question 4

why does cold water affect reptiles more than birds and mammals

Answer 4

Because birds and mammals regulate their own body temperatures.
SIDE NOTE IMPORTANT- Endotherms use internally generated heat to maintain body temperature. Their body temperature tends to stay steady regardless of environment. Ectotherms depend mainly on external heat sources, and their body temperature changes with the temperature of the environment.

Question 5

explain how fire can be beneficial in the Australian bushland

Answer 5

bushfires help provide nutrients that native vegetation specifically needs to rejuvenate and seed. heats the soil, cracking seed coats and triggering germination

Question 6

Compare:
Community and ecosystem:

Answer 6

An ecosystem is all the living organisms and environmental factors that interact within a given area. A community is only the living organisms that interact within a given area

Question 7

Distinguish between species diversity and genetic diversity and explain the importance of both of these to our definition of total biological diversity.

Answer 7

Genetic diversity is all the different genes contained in all individual plants, animals, fungi, and microorganisms. It occurs within a species as well as between species. Species diversity is all the differences within and between populations of species, as well as between different species. Both are important because they strengthen the ability of species and populations to resist diseases, pests, changes in climate and other stresses. Gene variations underpin their capacity to evolve and their flexibility to adapt.

Question 8

Explain the importance of considering ecosystem (habitat) diversity when targeting regions for conservation purposes.

Answer 8

Because human civilization activity contributes to the successive and accelerating process of biodiversity reduction by dying out species of living organisms.

Question 9

What is a biodiversity hotspot

Answer 9

’ places on Earth that are both biologically rich — and deeply threatened. For our own sake, we must work to protect them.

Question 10

The Gradient of Abiotic Factors:

Answer 10

• Within an ecosystem, there will be a variation in levels of any abiotic factor.
• These variances are affected by the other abiotic and biotic factors in the system
• This range of abiotic levels is called a gradient
• The ranges of abiotic factors influence the diversity of life forms in a particular ecosystem

Question 11

Tolerance Limits:

Answer 11

• Organisms have tolerance limits for a range of environmental factors. E.G. temperature, oxygen concentration, humidity, crowding, noise and light.
• If the environmental factor exceeds the limits of tolerance of that organism, then the organism will become stressed and die
• Example: an organism can survive and remain active only within a particular range of temperatures. The highest and lowest temperatures at which an organism can survive is called its tolerance limits for temperature.

Question 12

Describe an example of each of the following types of distribution pattern? Clumped, Random, Uniform

Answer 12

Clumped- A clumped dispersion may be seen in plants that drop their seeds straight to the ground—such as oak trees

Random- An example of random dispersion comes from dandelions and other plants that have wind-dispersed seeds

Uniform- Desert shrubs and redwood trees grow in a uniform distribution—shrubs compete for water, while redwoods compete for light.

Question 13

Scientists have identified approximately 1.8 million different species. The number of species that actually exist is likely to be significantly higher than 1.8 million.
Suggest two reasons why the number of species identified is likely to be lower than the actual number of species present on earth?

Answer 13

One reason is that they could not have found all species [e.g. some (named) habitats inaccessible / microscopic species missed
o -evolution is on-going
o some (species) difficult to distinguish

Question 14

What are the ways the nitrogen is fixed?

Answer 14

Nitrogen is fixed, or combined, in nature as nitric oxide by lightning and ultraviolet rays, but more significant amounts of nitrogen are fixed as ammonia, nitrites, and nitrates by soil microorganisms.

Question 15

Why is nitrogen essential?

Answer 15

Nitrogen is an essential nutrient for the production of amino acids, proteins, nucleic acids

Question 16

Name the process that releases nitrogen gas into the atmosphere

Answer 16

Denitrification

Question 17

State the form in which nitrogen is available to most plants

Answer 17

Nitrate

Question 18

Describe how animals acquire the nitrogen they need

Answer 18

Animals get the nitrogen they need by eating plants or other animals that contain nitrogen

Question 19

Explain why farmers may plough a crop of legumes into the ground rather than harvest it

Answer 19

By plowing these roots into the soil, the nitrogen content in the soil would increase.

Question 20

How does the concept of limiting factors apply to population biology:

Answer 20

THEY REGULATE HOW MANY ORGANISMS LIVE IN ENVIRONMENT. Limiting factors- things like water and temperature, can constrain a population’s size or stops it from growing.

Question 21

what is * Primary Succession:

Answer 21

colonization of an area, not previously occupied by an ecological community (example to come).
Might occur following lava flow, glacial retreat or volcanic eruptions.

Question 22

what is Secondary Succession:

Answer 22

successional dynamics following severe disturbance/ removal of a pre-existing community.
Might occur following bush fires or land clearing.

Question 23

answer the following short questions:
* Describe situations in which a primary succession is likely to occur:
* Identify Pioneers during the colonisation of bare rock:
* Define two important roles of the species that are early colonisers of bare soils:

Answer 23

when new land is formed or bare rock is exposed

bacteria and lichens that can grow on bare rock and help make soil.

prepare and fertilize the soil for producers.

Question 24

Why does a secondary succession proceed more rapidly than a primary succession?

Answer 24

Secondary succession is a faster process than primary succession because some cones or seeds likely remain after the disturbance.

Question 25

Name an important pioneer in secondary successions in Australia:

Answer 25

Succession – process where life comes back after disturbance
Pioneer- animals that come in after a disturbance
Climax- at the end of succession
Primary- soil
Secondary- no soil

Question 26

what are keystone species

Answer 26

species that are crucial to the way all other species interrelate

Question 27

Unicellular vs multicellular

Answer 27

Unicellular- too small to be visible- need a microscope. Organelles. Have a low level of efficiency. Cannot grow large cuz they are limited by surface area to volume ratio. Food is engulfed and stored in food vacuums.
Multi- multiple cell and are more complex. Allows organism to be larger and some differentiates. Different cells to carry out different tasks. Highly efficient. Increase number of small cells to get a large number of cells overall.

Question 28

prokaryote vs eukaryote

Answer 28

prokaryote -
Commonly knowns as bacteria
o 10-100 microns in size
o Single celled (unicellular) or
o Filamentous (strings of single cells)
Eukaryotes
are bigger and more complicated:
o Have organelles
o Have chromosomes
o Can be multicellular
o Include animal and plant cells
biggest distinction between them is that eukaryotic cells have a distinct nucleus containing the cell’s genetic material, while prokaryotic cells don’t have a nucleus and have free- floating genetic material instead.

Question 29

what are organelles

Answer 29

membrane bound cell parts
* Mini ‘organs’ that have unique structures and functions
* Located in cytoplasm

Question 30

Describe homeostasis

Answer 30

A state of balance among all the body systems needed for the body to survive and function correctly. The maintenance of stable internal conditions in a cell or organism despite changing internal and external conditions.

Question 31

Identify the two main mechanisms of homeostasis

Answer 31

Negative feedback loops- (Changes in a variable being monitored triggers an inhibition of that variable). These loops aim to stabilise a variable at a constant level. They would stabilise by slowing or stopping change.
Example is temperature control.
Positive feedback loops: (change in variable being monitored triggers an amplification of that variable). These loops aim to ensure the conclusion of some event. Example is labour contractions. Its going to keep going up and up and up until we get that conclusion.

Question 32

answer following short answer questions:
Explain the purpose of thermoregulation:
Identify the ways in which organisms thermoregulate:
Distinguish between endotherm and ectotherms:

Answer 32

To regulate body temperature
convection, radiation, conduction, evaporation
Ecto= heat from outside
Turtles. Derive temperature from surroundings so they are room temp. they don’t have to burn up energy inside of themselves. So, they don’t require a huge amount of energy.
Endo= generating heat inside you- metabolism. Internal temp is the same, but you have to constantly eat. We use negative feedback loop.