B3 - Life on Earth

Question 1

Adaptations

Answer 1

Features that help an organism survive in the environment it lived in and reproduce successfully.

Question 2

What do animals compete for?

Answer 2

Food, a mate, living space, water and territories

Question 3

What do plants compete for?

Answer 3

Light, water, space, mineral salts

Question 4

Interdependence

Answer 4

The mutual dependence an organism has on another to help them survive

Question 5

Name two species that human activity is threatening:

Answer 5

The Siberian tiger and the Mountain gorilla

Question 6

3 reasons why some energy is lost as it is passed down the food chain:

Answer 6

• Some parts of the plant aren’t eaten or can’t be digested by the animal
• The animal uses some of the plant’s energy for respiration, during respiration some energy is lost as heat
• The waste products of the animal, such as urine, contain some energy

Question 7

What is the equation for percentage efficiency?

Answer 7

Energy in tissues
———————— x 100
Energy in food eaten

Question 8

Decomposers

Answer 8

Microorganisms, such as bacteria which feed on dead or decaying organisms.

Question 9

Detritus

Answer 9

Partly decayed material

Question 10

What are detrivores? Give 2 examples:

Answer 10

Detrivores, such as earthworms and woodlice, feed on detritus and break it down further

Question 11

How does Carbon enter the Carbon Cycle?

Answer 11

As carbon dioxide from the air, plants fix this carbon so that it can be used by organisms

Question 12

How is Carbon returned to the air in the Carbon Cycle?

Answer 12

• As a product of respiration
• Through the decomposition of dead organisms by soil microorganisms
• By Combustion of organic materials

Question 13

How does Nitrogen enter the Nitrogen Cycle?

Answer 13

• Nitrates are released back into the soil as animals excrete waste and as plants and animals die and are decomposed
• Nitrogen molecules in the air are split by lightning. Nitrogen atoms then combine with oxygen in the air to form nitrates, which are washed into the soil by rain
• Nitrogen-fixing bacteria found in the soil and in the roots of plants convert nitrogen in the air into nitrates

Question 14

How does Nitrogen leave the Nitrogen Cycle?

Answer 14

It leaves the cycle when denitrifying bacteria convert nitrates in the soil into nitrogen gas.

Question 15

Denitrification

Answer 15

When denitrifying bacteria convert nitrates in the soil into nitrogen gas.

Question 16

What are the two types of indicators of environmental change?

Answer 16

Non living and living

Question 17

Examples of non-living indicators: give two

Answer 17

Carbon dioxide levels, temperatures, nitrate levels

Question 18

Examples of living indicators: give two

Answer 18

Phytoplankton, Lichen and Mayfly Larvae

Question 19

What are Phytoplankton?

Answer 19

Microscopic aquatic plant-like organisms

Question 20

What are lichen?

Answer 20

Dual organisms made up of fungus and algae living together

Question 21

Biotic index

Answer 21

When Observations of some living indicators can give us very precise information about levels of pollution and environmental change

Question 22

How long ago did life on earth begin?

Answer 22

Around 3500 million years ago

Question 23

Fossils

Answer 23

The remains of organisms or other traces of their lives that have turned into rock

Question 24

Mutation

Answer 24

A change in the genetic information in a cell

Question 25

The gene pool

Answer 25

The alleles of genes that occur in a population

Question 26

Natural selection

Answer 26

The process during which individuals with advantageous genes will survive to reproduce and pass these genes to their offspring

Question 27

What does selective breeding involve:

Answer 27

* Choosing the individuals with the characteristics that are closest to those required * Breeding these and preventing others from breeding * Repeating the process over several generations

Question 28

What do scientists do to investigate evidence of evolution?

Answer 28

* Examine the fossil record * Observe similarities and differences in physical features * Analyse DNA sequences

Question 29

What evidence is there to support the theory of Evolution?

Answer 29

* The simplest organisms are found in the earliest rocks. More complex ones appear in younger rocks * More recent fossils have features that look like adaptations or developments of those of older organisms * DNA analysis of today's organisms has confirmed predictions made from the fossil record, including when branches in the tree of life occurred

Question 30

Who produced the theory of evolution and when?

Answer 30

Charles Darwin and Alfred Russel Wallace in 1859

Question 31

Common ancestor

Answer 31

The most recent organism from which the species in a group descended

Question 32

Biodiversity

Answer 32

Variety of life of earth and in different habitats

Question 33

Kingdom

Answer 33

A large group containing many organisms with a small number of characteristics in common

Question 34

Species

Answer 34

A small group of few organisms with a high number of characteristics in common

Question 35

Sustainability

Answer 35

Meeting today's need without stopping future generations from meeting theirs

Question 36

Monoculture

Answer 36

The continuous production of one type of crop

Question 37

Advantage of monoculture

Answer 37

•It can be done efficiently

Question 38

Disadvantages of monoculture

Answer 38

* If pests or disease attacked the crop it could harm it easily * Farmers' use of pesticides and herbicides can harm the environment so monoculture isn't sustainable * If a natural disaster was to occur the whole crop would be wiped out * The use of pesticides and herbicides reduces the variety of species and hinders biodiversity

Question 39

How can we improve the sustainability of product manufacture

Answer 39

* Using as little energy as possible and minimal packaging * Using locally available materials and limiting transport of the product * Creating as little pollution as possible

Question 40

Biodegradable

Answer 40

Materials which break down faster compared to non biodegradable ones

Question 41

Species

Answer 41

A group if organisms that can breed together to produce fertile offspring