4.1

Question 1

Define Species

Answer 1

A group of organisms that can potentially interbreed to produce
fertile offspring
eg. Canis lupus, Linnea borealis

Question 2

Define Population

Answer 2

A group of organisms of the same species living in the same area at the same time
eg. Whales in Atlantic in Summer,
Dandelions in a garden in Spring

Question 3

Define Community

Answer 3

Populations of different species living together in the same place at the same time, interacting with each other
eg. all living organisms in the school pond in September, All living organisms in the amazon rainforest in 2010

Question 4

Define Habitat

Answer 4

An area where a population/community lives

eg. desert, pond, Arctic

Question 5

Define an ecosystem

Answer 5

An ecosystem is formed when a biotic community interacts with the abiotic environment
eg. all living things in school pond & effects of temperature, light intensity

Question 6

Define Ecology

Answer 6

The study of the relationship between living organisms & between living organisms and their environment

Question 7

Species:

Brief notes on Asexual Reproduction

Answer 7

Some species may reproduce asexually without interbreeding to produce genetically identical offspring eg. aphids, hydra, bacteria

However, many species can reproduce sexually to maintain genetic diversity

Question 8

Species:

Brief notes on cross-breeding

Answer 8

Occasionally, members of different species can breed together to produce offspring eg. tigon, mule, liger

However, cross-breeding almost always produces infertile offspring

Question 9

Populations:

What may happen over time if two isolated populations of a species never interbreed?

Answer 9

Geographical separate populations may gradually over time develop different characteristics (natural selection)

Eventually the differences may become so great individuals from the population can’t breed to produce fertile offspring (different species)

Question 10

What is an Autotroph?

Answer 10

Organisms that synthesise their own

organic compounds from simple inorganic molecules

Question 11

What is a Heterotroph?

Answer 11

An organism that obtains organic compounds from other organisms

Question 12

What is a consumer?

Answer 12

organisms that ingest other organisms that aren’t living or have recently been killed

Question 13

What is a detritivore?

Answer 13

An organism that obtains organic nutrients from waste & dead organisms by internal digestion
eg. earthworms, woodlice

Question 14

What is a saprotroph?

Answer 14

An organism that obtains organic nutrients from waste & dead organisms by external digestion
eg. fungi, bacteria

Question 15

Interactions:

What is Predation/Herbivory

Answer 15

A consumer feeding on another animal (predation) or plant (herbivory)
eg. lion eating gazelle, tadpoles eating pond weed

Question 16

Define Competition for resources

Answer 16

Animals compete for: food, water, territory, mates

Plants compete for: light, space, minerals, water

eg. woodpeckers & squirrels compete for nesting rights in a hole of a tree

Question 17

What is mutualism/symbiosis

Answer 17

When two different species live together in a close relationship where both benefit

eg. Oxpeckers eat ticks & flies from skin of impalas. Oxpeckers get nourishment and impalas get pest control

Question 18

What is parasitism?

Answer 18

When one organism lives on or in another organism (the host) & causes it harm

eg. female hawk wasps parasitise a spider by stinging & paralysing it w/ venom, then allaying eggs in its body. The babies then hatch & eat the living spider alive

Question 19

Outline how the supply of inorganic nutrients is maintained by nutrient cycling

Answer 19

Autotrophs concert inorganic nutrients into organic molecules

Heterotrophs ingest organic molecules and may release byproducts (CO2)

Saprotrophs break down nutrients in dead organism and return them to the soil (decomposes)

• Energy enters in the form of light and is converted into chemical energy by producers
• Most of this energy is lost as heat & radiated back into environment
• Nutrients aren’t lost, but recycled & reused

Question 20

Sustainability of Ecosystems

Answer 20

Human uses of resources aren’t sustainable:
We are using up fossil fuels faster than they’re made & We are producing toxic waste products from them

3 requirements for sustainable ecosystem:

• Supply of nutrients
• Source of energy for nutrient assimilation
• Detoxification of waste products

We can be more sustainable is we recycle plastics, compost, use renewable energy sources