Unit 3 Life on Earth

Question 1

What does biodiversity mean?

Answer 1

Biodiversity is the number of different species in a ecosystem

Question 2

What is a ecosystem?

Answer 2

Natural biological unit made up of living and non living parts

Question 3

What is a habitat?

Answer 3

The place where an organism lives

Question 4

What is a community?

Answer 4

All the living organisms that live within a habitat

Question 5

What is a population?

Answer 5

A group of living organisms of the same species eg a herd of sheep

Question 6

what is a species?

Answer 6

a group of organisms that can produce offspring

Question 7

What is a producer?

Answer 7

an organisms that produces its own food

Question 8

what is a consumer?

Answer 8

an organism that gets energy by eating other organisms

Question 9

what is a herbivore?

Answer 9

only eats plants

Question 10

what is a carnivore?

Answer 10

only eats meat/other animals

Question 11

what is a omnivore?

Answer 11

eats plants and animals/meat

Question 12

what is a niche?

Answer 12

the role an organism plays within its ecosystem

Question 13

what is interspecific competition?

Answer 13

competition between different species, for one or a few recourses they require

Question 14

what is intraspecific competition?

Answer 14

competition within the same species, for all of the recourses they require

Question 15

what competition is more intense?

Answer 15

intraspecific

Question 16

what type of competition is more intense?

Answer 16

intraspecific competition

Question 17

what are abiotic factors?

Answer 17

non living variables
- light intensity
- temperature
- soil pH

Question 18

how do you measure abiotic factors and the precautions needed when using them?

Answer 18

• light meter : don’t shade it
• thermometer : wipe down the probe afterwards
• moisture probe : wipe down probe afterwards

Question 19

what are biotic factors?

Answer 19

living factors
- predation
- disease
- food availability

Question 20

how to sample biotic factors and precautions needed when doing it?

Answer 20

• quadrats : make sure to place quadrats randomly
• pitfall traps : must be covered so water can’t get in

Question 21

what are indicator species?

Answer 21

species that indicate environment quality and pollution levels by their presence or absence
eg lichens, pollution indicators

Question 22

what is the photosynthesis equation?

Answer 22

light energy
water+carbon dioxide——>oxygen+sugar
chlorophyll

Question 23

Where is light absorbed in the cell?

Answer 23

the chlorophyll found in chloroplasts

Question 24

what is the first stage of photosynthesis?

Answer 24

Light reactions
-light from sun captured in chlorophyll and converted to chemical energy to make ATP
- water is split to make hydrogen and oxygen

Question 25

What is stage 2 of photosynthesis?

Answer 25

Carbon Fixation -series of enzyme controlled reactions -hydrogen and ATP from light reactions combine with carbon dioxide to make sugar

Question 26

what ways can the sugar produced by photosynthesis be used?

Answer 26

-energy source (used in respiration) -energy storage (starch) -building material (cellulose)

Question 27

what are the limiting factors of photosynthesis?

Answer 27

-carbon dioxide concentration -light intensity -temperature

Question 28

how can energy be lost when being passed onto the organism that consumes it?

Answer 28

-heat -movement -undigested materials

Question 29

what organisms use part of the lost energy from an organism?

Answer 29

decomposers consume dead plants and animals

Question 30

how much energy is lost within a food chain and how much is passed on?

Answer 30

90% is lost and only 10% is passed on

Question 31

what does an increase in human population require?

Answer 31

an increase in food yield food yield - volume of food frown/harvested

Question 32

what are two common ways to increase crop yield?

Answer 32

pesticides - chemicals used to kill pests that damage crops fertilisers - substance added to soil to increase fertility (increase nitrate content is soil)

Question 33

what are the problems of pesticides?

Answer 33

could accumulate in bodies of organisms over time, as passed along the food chain toxicity builds up and can become lethal

Question 34

what are pesticide alternatives?

Answer 34

genetically modified crops, biological control

Question 35

what are examples of natural fertiliser?

Answer 35

compost, manure, ploughing clover

Question 36

what are alternatives to fertilisers?

Answer 36

genetically modified

Question 37

how do plants absorb nitrogen?

Answer 37

-nitrates dissolved in soil water are absorbed by roots -nitrates produce amino acids and are synthesised into plant proteins -animals consume plants or other organisms to obtain amino acids for protein synthesis

Question 38

what are the problems of fertilisers?

Answer 38

fertilisers can leach into fresh water, that cause an algal bloom, this leads to a reduction in oxygen levels

Question 39

what are the stages of algal bloom?

Answer 39

1. fertilisers leach into fresh water 2. increases algal population, causing algal bloom 3. reduces light levels, killing aquatic plants 4. bacteria feed on dead plants, and dead algae so bacteria increases 5. bacteria use up lots of oxygen, reducing oxygen for other organisms

Question 40

what are mutations?

Answer 40

a random change in a organisms genetic information

Question 41

what are factors that increase mutation rates?

Answer 41

chemical - mustard gas, cigarette smoke radiation - UK rays, X rays

Question 42

what is an advantageous mutation?

Answer 42

some mutations can give an organism an advantage

Question 43

what is a neutral word mutation?

Answer 43

mutations that can neither be an advantage nor disadvantage to the organisms survival

Question 44

what are disadvantageous mutations?

Answer 44

is a disadvantage of the survival of the organism

Question 45

what is natural selection?

Answer 45

natural selection is the survival of organisms best suited to their environment also known as survival of the fittest

Question 46

what is speciation?

Answer 46

the formation of a new species

Question 47

what are the different barriers?

Answer 47

- geographical barrier - ecological barrier - reproductive barrier

Question 48

how does speciation occur?

Answer 48

after a part of a population becomes isolated by a barrier different mutation occur in each of the sub populations, each sub population evolves until,they become so different they are two different species