B3 - Life on Earth

Question 1

What is a species?

Answer 1

a group of organisms that can breed together to produce fertile offspring

Question 2

What does adaptation of living organisms to their environment do?

Answer 2

increases the species’chance of survival by making it more likely that individuals will survive to reproduce

Question 3

What are living organisms dependent on for their survival/

Answer 3

The environment and other species

Question 4

there is ___________ for resources between different species of animals or plants in the same habitat

Answer 4

competition

Question 5

explain the interdependence of organism living in a food web

Answer 5

Use diagram in the exam

If one animals numbers increases this will effect predators/prey etc

Question 6

When do changes in environment cause animals to become extinct?

Answer 6

a. the environmental conditions change beyond its ability to adapt
b. a new species that is a competitor, predator or disease organism of that species is
introduced
c. another species (animal, plant or microorganism) in its food web becomes extinct

Question 7

What are all organisms ultimately dependent on for energy?

Answer 7

The Sun

Question 8

How is energy transferred between organism in an ecosystem?

Answer 8

a. when organisms are eaten
b. when dead organisms and waste materials are fed on by decay organisms
(decomposers and detritivores)

Question 9

How does energy pass out of the food chain at each stage?

Answer 9

via heat, waste products and

uneaten parts, limiting the length of food chains

Question 10

How can energy efficiency be calculated at each stage?

Answer 10

energy transferred to next level ÷ total energy in × 100

Question 11

How is carbon recycled through the natural environment?

Answer 11

the processes of combustion (it is released), respiration(it is released), photosynthesis(it is absorbed) and decomposition (it is produced)

Question 12

What is the importance of the role of microorganisms in the carbon cycle?

Answer 12

They decompose matter. Decomposition is crucial for the completion of the Carbon Cycle, since it is the only way that the carbon trapped in dead organic matter can be recirculated into the atmosphere, where plants capture it for the building of new organisms.

Question 13

How is nitrogen recycled through the natural environment?

Answer 13

a. nitrogen fixation to form nitrogen compounds including nitrates
b. conversion of nitrogen compounds to protein in plants and animals
c. transfer of nitrogen compounds through food chains
d. excretion, death and decay of plants and animals resulting in release of nitrates into the
soil
e. uptake of nitrates by plants
f. denitrification

Question 14

What is nitrogen fixation?

Answer 14

Making nitrogen compounds from nitrogen in the air

The energy in lightning splits nitrogen molecules into individual nitrogen atoms. These react with oxygen to form nitrogen oxides. Nitrogen oxides are washed to the ground by rain, where they form nitrates in the soil

Nitrogen-fixing bacteria found in the soil and in the root nodules of leguminous plants, such as peas, beans and clover, fix nitrogen gas into nitrogen compounds

Question 15

What is the importance of the role of microorganisms in the nitrogen cycle? ( decomposition)

Answer 15

decomposition - Urea and egested material is broken down by decomposers. This results in nitrogen being returned to the soil as ammonia.

Question 16

What is the importance of the role of microorganisms in the nitrogen cycle? ( nitrogen fixation)

Answer 16

nitrogen fixation -Nitrogen gas is converted to nitrate compounds by nitrogen-fixing bacteria in soil or root nodules

Question 17

What is the importance of the role of microorganisms in the nitrogen cycle? ( denitrification)

Answer 17

denitrification - In some conditions denitrifying bacteria in the soil break down nitrates and return nitrogen to the air. This is usually in waterlogged soil. Improving drainage reduces this effect, making the soil more fertile

Question 18

How can environmental changes be monitered using non-living indicators?****

Answer 18

phytoplankton, lichens and aquatic river organisms such as mayfly nymphs - update

Question 19

When did life on Earth begin?

Answer 19

Approx 3500 million years ago

Question 20

All species evolved from ________

Answer 20

very simple living things

Question 21

How is variation in a species passed on?

Answer 21

there is variation between individuals of the same species and that some of this variation is genetic so can be passed on to offspring

Question 22

What is genetic variation a result of?

Answer 22

genetic variation is the result of changes that occur in genes (mutations)

Question 23

What can mutated genes in sex cells do?

Answer 23

mutated genes in sex cells can be passed on to offspring and may occasionally produce new characteristics

Question 24

What is a summary of natural selection?

Answer 24

the effects of genetic variation and
competition on survival and reproduction, leading to an increase in the number of individuals
displaying beneficial characteristics in later generations

Question 25

What are the similarities and differences between natural selection and selective breeding?

Answer 25

Natural selection and selective breeding can both produce changes in animals and plants. The difference between the two is that natural selection occurs in nature, but selective breeding only occurs when humans intervene(humans ‘choose’ the desirable characteristics)

Question 26

How can the combined effect of mutations, environmental changes, natural selection
and isolation produce new species in the process of evolution?

Answer 26

The changes created can be so big a new species is produced. This does not happen very often and only occurs when the mutated organism can no longer breed with the original species and is capable of producing fertile offspring.

Question 27

How is evidence for evolution provided?

Answer 27

evidence for evolution is provided by the fossil record and from analysis of
similarities and differences in the DNA of organisms

Question 28

Why was Darwin’s theory of evolution better than Lamarck’s?

Answer 28

Lamarck’s theory cannot account for all the observations made about life on Earth. For instance, his theory would predict that all organisms gradually become complex, and simple organisms disappear.
Darwin’s theory can account for the continued presence of simple organisms.
Darwin’s fits with advances in understanding of genetics

Lamarck’s had no evidence or mechanism for
inheritance of acquired characteristics)

Question 29

Organisms are classified into groups according to similarities and differences
in characteristics including what?

Answer 29

a. physical features (e.g. flowers in flowering plants and the skeleton in vertebrates)
b. DNA

Question 30

How are the levels of classification of organisms arranged?

Answer 30

these levels can be arranged in an order progressing from large groups containing many organisms with a small number of characteristics in common (e.g. kingdom) to smaller groups containing fewer organisms with more characteristics in common (e.g. species)

Question 31

What can classification of living and fossil organisms help to do?

Answer 31

a. make sense of the enormous diversity of organisms on Earth
b. show the evolutionary relationships between organisms

Question 32

Biodiversity refers to the variety of life on Earth, including what?

Answer 32

a. the number of different species
b. the range of different types of organisms, e.g. plants, animals and microorganisms
c. the genetic variation within species

Question 33

understand why biodiversity is important for the future development of food crops and
medicines**

Answer 33

……..

Question 34

understand that the rate of extinction of species is increasing and why this is likely to be due to
human activity*******

Answer 34

…………

Question 35

What is one of the keys to sustainability?

Answer 35

Maintaining biodiversity to ensure the conservation of different species

Question 36

What does sustainability mean?

Answer 36

Sustainability means meeting the needs of people today without damaging the Earth for future generations

Question 37

Why is large-scale monoculture crop production not sustainable?

Answer 37

It doesn’t maintain biodiversity

Question 38

How can sustainability be improved?

Answer 38

for example in the use of packaging

materials, by considering the materials used, energy used and pollution created

Question 39

Why is it preferable to decrease the use of some materials, including packaging materials, even when they are biodegradable?

Answer 39

a. use of energy in their production and transport

b. slow decomposition in oxygen deficient landfill sites.