Biology Higher 4 GCSE (only B4 and B5)

Question 1

define an ecosystem

Answer 1

the living and physical conditions in an area

Question 2

define a community

Answer 2

the organisms within an ecosystem

Question 3

define a habitat

Answer 3

the area in which a community lives

Question 4

define population

Answer 4

the total number of organisms in an area

Question 5

producers

Answer 5

plants and organisms that can make up their own food.

Question 6

consumers

Answer 6

they are unable to make their own food and have to eat producers to gain energy

Question 7

decomposers

Answer 7

they gain energy by breaking down dead or decaying material.

Question 8

biotic factors

Answer 8

living factors

like number of trees, squirrels etc.

Question 9

abiotic factors

Answer 9

non-living factors

like light intensity, temperature, pH, moisture level.

Question 10

what is competition

Answer 10

when animals compete fr limited resources

Question 11

what do animals need

Answer 11

food
water
breeding partner
space
shelter

Question 12

what do plants need

Answer 12

light 
water
carbon dioxide
minerals 
space

Question 13

3 types of interdependance

Answer 13

predation
mutualism
parasitism

Question 14

how may energy be lost between trophic levels

Answer 14

not all of the organism is eaten
some of the biomass may be used in respiration, which produces ATP for movement and heat
Indigestible parts of an animal- hair, nails
waste products

Question 15

efficiency of biomass transfer

Answer 15

efficiency of biomass transfer=

biomass after transfer/ biomass before transfer *100

Question 16

how does nitrogen go from the air to plants

Answer 16

nitrogen-fixing bacteria that mix oxygen with nitrogen in the air to make nitrates

Question 17

how does ammonia in the soil get absorbed by plants

Answer 17

nitrifying bacteria turns ammonia into nitrates

Question 18

how do nitrates turn back into nitrogen in the atmosphere

Answer 18

denitrifying bacteria releases nitrogen

Question 19

what is percolation

Answer 19

when water trickles through soils and rocks to join the river

Question 20

why do the levels of carbon dioxide vary during the day

Answer 20

photosynthesis only takes place during the day- so co2 in only removed during the daylight
respiration happens 24/7 so co2 is continued to be added the entire day

Question 21

whats the difference between a decomposer and a detritivore

Answer 21

decomposers are microorganisms. they break down or decay organic material at a microscopic level.
detritivores are small animals that speed up decomposition by breaking down organic material into smaller pieces.

Question 22

how do bacteria release nutrients

Answer 22

they release enzymes on the dead remains
the enzymes can then digest the dead matter and make it soluble (dissolve-able)
the soluble products are absorbed by the fungus

Question 23

what factors affect the rate of decomposition

Answer 23

warm temperatures
Moist environments: needs water to decompose
aerobic conditions: oxygen is needed for the microorganisms to respire.

Question 24

rate of decay

Answer 24

rate of decay = change in mass (g)/ time (day)

Question 25

phenotype

Answer 25

the appearance of an organism

Question 26

what is variation

Answer 26

difference within a species

Question 27

genetic variation and environmental variation

Answer 27

genetic- physical genetic material in an organism (dna) | environmental- the environment in which you live in

Question 28

discontinuous variation

Answer 28

individuals that show characteristics that fall into distinct groups, such as blood groups

Question 29

continuous variation

Answer 29

can have any value between minimum and maximum

Question 30

asexual reproduction

Answer 30

``` usually produces clones examples: potato plants spider plants daffodils ```

Question 31

sexual reproduction

Answer 31

requires 2 parents its offspring isn't identical since it uses 2 pair of genes it produces sex cells called gametes that fuse together in fertilisation.

Question 32

advantages and disadvantages of asexual reproduction

Answer 32

advatages: if the parent can adapt well to an area, so can the offspring only one parent is needed- so its quicker to reproduce disadvantage: if there is a change to biotic or abiotic changes, it may destroy the entire species

Question 33

advantages and disadvantages of sexual reproduction

Answer 33

advantage: variation in offspring leads to adaptations in a species disadvantage: reproduction requires 2 parents. It is much slower so fewer offspring are produced

Question 34

differences between diploid and haploid cells

Answer 34

diploid: 46 chromosomes haploid: 23 chromosomes

Question 35

what is a zygote

Answer 35

a fertilised egg cell

Question 36

meiosis

Answer 36

produces gametes | which are haploid cells (23)

Question 37

chromosomes for male

Answer 37

XY

Question 38

chromosomes for female

Answer 38

XX

Question 39

history of genetics

Answer 39

1866- Gregor Mendel carried out an experiment on peas He noticed that characteristics were determined by hereditary units (now called genes) They are passed on from both parents and they are either dominant or recessive 1869- Nuclein discovered Friedrich Miescher discovered there is an acidic substance present in each nucleus (DNA) 1944- Genes can be transferred from one generation to another 1950- DNA base pairs found by Erwin Chargaff 1952- DNA crystals photographed by Maurice Wilkins and Rosalind Franklin 1953- Double helix structure James Watson and Francis Crick 1953- 2000 - Identified individual genes that code for genetically inherited disorders 2003- Human genome project completed- they discovered 24000 genes

Question 40

evolution

Answer 40

a gradual change in species over time

Question 41

explain natural selection

Answer 41

1. Organisms show variation caused by a difference in their genes 2. The organisms with the characteristics that are best adapted will survive 3. genes from the successful will be passed down to their offspring 4. the process is then repeated many times

Question 42

examples of evolution

Answer 42

peppered moths- before the industrial revolution, moths were pale. then a mutation made them dark coloured, but they didn't survive because they couldn't camouflage against the light coloured trees after the industrial revolution, the trees were covered in soot so they became dark and the darker moths became more camouflaged against them, so they survived longer

Question 43

how are fossils made

Answer 43

1. the reptile dies 2. the flesh rots, leaving the skeleton covered in sand and soil before it is damaged 3. protected over millions of years, it becomes mineralised and turns to rock 4. eventually, the fossils emerge as the rocks move and erosion takes place

Question 44

how does the fossil record provide evidence for evolution

Answer 44

fossils of the simple organisms are generally much older compared to the more complex ones that are much younger plant fossils appear before animal ones- so animals clearly needed plants closely related organisms came from the same ancestor and this can be found by studying their anatomy

Question 45

what other evidence is there for evolution

Answer 45

rapid change in species- as bacteria can replicate, scientists can study evolution in action and observe the changes extinction- species that are unable to adapt to environmental changes usually die out molecular comparison- scientists have began to compare the DNA and proteins of different species and the order of nucleic orders etc.

Question 46

Theory of evolution

Answer 46

He joined a scientific expedition to the Galapogas Islands and he made his observation on finches. He saw that the beaks of the finches was entirely based on the types of food that they ate. At the same time that Charles Darwin was developing his theory, Alfred Russel Wallace gathered evidence for his theory, which was overall very similar to Darwin's so they did a joint report.

Question 47

Binomial nomenclature

Answer 47

A universal system of naming species. The first name is the organism's genus. The second name is the organism's actual name

Question 48

Classification system

Answer 48

``` Kingdom Phylum Class Order Family Genus Species ```

Question 49

Natural classification

Answer 49

looking for a common ancestor. the study of evolutionary links is known as phylogeny.

Question 50

artificial classification

Answer 50

they group together organisms based off of their physical, observable characteristics.

Question 51

define a species

Answer 51

a group of organisms that share the same genetic material and can breed to have fertile offspring

Question 52

A research team want to genetically engineer pigs so that they produce organs that are not rejected by humans. Describe how they could do this

Answer 52

``` Identify gene for human tissue types isolate this gene insert this gene into the pig embryo replicate the gene check the cell for expression of the gene ```

Question 53

how is malaria spread

Answer 53

an example of protozoa mosquitoes suck blood out of someone with malaria then pass it on

Question 54

what happens to a person's lungs when they are having an asthma attack

Answer 54

airways become swollen and restrict air flow. | muscles around bronchiols contract

Question 55

why is the ozone layer reducing

Answer 55

people using CFCs, refrigeration | greenhouse gases increased