B1 Part B

Question 1

How are desert animals adapted to survive, save water and keep cool? (5)

Answer 1

• Large surface area in comparison to volume, lets them lose more body heat
• Produce small amounts of concentrated urine
• Make very little sweat (to conserve water)
• Thin layers of body fat and coat to help them lose body heat
• A sandy colour gives them camouflage to avoid predators

Question 2

How are animals from cold climates adapted? (3)

Answer 2

• Small surface area in comparison to volume to minimise heat loss
• Well insulated - layers of blubber (energy source)
• Thich hairy coats and greasy fur sheds water (prevents cooling due to evaporation)

Question 3

List all the ways a cacti is adapted for desert climates

Answer 3

• Plants lose water vapour from their leaves so cacti have spines instead
• They have a small surface area compared to their volume
• Stores water in its thick stem
• Shallow but extensive roots absorb water quickly over a large area (other plants have deep roots to access underground water)

Question 4

List three ways an animal or plant might be adapted to deter predators

Answer 4

• Armour (eg sharp thorns or shells)
• Produce poisons (eg bees and poison ivy)
• Warning colours (eg wasps)

Question 5

What are extremophiles?

Answer 5

Microorganisms that are adapted to live in extreme climates with high temperature/high pressure/high concentration of salt

Question 6

What resources do plants compete for? (4)

Answer 6

• Light
• Space
• Water
• Minerals (nutrients from the soil)

Question 7

List four things that animals compete for

Answer 7

• Space (territory)
• Food
• Water
• Mates

Question 8

Which 4 living and 3 non living factors can cause environmental change?

Answer 8

Living: occurence of infectious disease, number of predators, availability of prey/food sources, number of competitors

Non- living: average temperature, average rainfall, air or water pollution

Question 9

Why might a population size increase?

Answer 9

If the amount of prey/available food source increases because more predators survive and reproduce

Question 10

Give an example of population decrease in a species and explain it

Answer 10

The number of bees in the world - could be sue to pesticides effecting their health and habitat, less food (nectar-rich plants), more disease (pathogens and parasites).

Question 11

Why might population distribution change?

Answer 11

The species may choose to migrate elsewhere due to a change in conditions eg. European Bee eater bird is originally Mediterranean but can now be found in Germany due to temperature rise

Question 12

How can environmental change be measured using living indicators? (3)

Answer 12

1. Lichen population indicates towards air pollution:
   • Bushy lichens need really clean air.
     Leafy lichens can survive a small amount of air pollution.
     Crusty lichens can survive in more polluted air.
2. Inverterbrate animals like mayflay are sensitive to the concentration of dissolved oxygen in water. Their presence indicates it is clean
3. Rat tailed maggots and sludgeworms indicate a very high level of water pollution

Question 13

Give four ways scientists are able to measure environmental change using technology

Answer 13

• Satellites measure the temperature of the sea surface and amount of snow
• Automatic weather stations tell us atmospheric temperature, thermometers are sensitive and accurate
• Rain gauges measure rainfall
• Dissolved oxgen meters measure how the level of water pollution changes

Question 14

What does each bar on a pyramid of biomass tell us?

Answer 14

The mass of living material on that stage of the food chain - how much the organisms would “weigh”.

Question 15

Name the stages in a pyramid of biomass

Answer 15

The bottom bar represents the producer (eg. plant), the next will be the primary consumer then the secondary consumer and so on.

Question 16

What entity provides energy for nearly all life on Earth?

Answer 16

The Sun

Question 17

Why is energy lost at each stage in pyramids of biomass? (4)

Answer 17

• Green plants and algae use energy to make food in photosynthesis
• Respiration in consumers uses energy
• Heat energy is lost as animals must maintain homeostasis
• Some material which makes up plants and animals is inedible to the next consumer (eg bones)

All of this explains why food chains are barely ever longer than five trophic levels - not enough energy to support more organisms.

Question 18

How are elements cycled back to the beginning of the food chain?

Answer 18

Decay. When organisms die their body (containing nutrients and elements) is broken down and digested by microorganisms.

Question 19

Why are plants so crucial to the food chain?

Answer 19

Plants take in carbon, oxygen, hydrogen and nitrogen from the soil/air. These are turned into complex compounds (carbohydrates, proteins, fats) that make up living organisms and pass through the food chain

Question 20

In what conditions do microorganisms that cause decay work best?

Answer 20

Warm and moist environments eg. compost bins

Question 21

Why does having a compost bin benefit your garden?

Answer 21

Kitchen waste is remains of animal and plant matter that can be decayed and the nutrients put back into the soil in your garden.

Question 22

Why is the food chain and process of decay described as a stable community?

Answer 22

The materials taken out of the soil and used are balanced by those that are put back in. It’s a constant cycle.

Question 23

Describe/draw a diagram of the carbon cycle

Answer 23

Question 24

Outline the processes in the carbon cycle (6 main points)

Answer 24

• Carbon dioxide in the atmosphere is absorbed by plants → eaten and digested by animals
• When plant and animal matter dies their carbon compounds will decay and enter the soil
• Animals also respire and release carbon back into the atmosphere
• Fossil fuels are made of decayed plant and animal matter → when fossil fuels are burnt this releases carbon dioxide into the atmosphere
• Products from plants and animal matter like wood, paper and leather are also burnt/decay to emit carbon into the environment
• Carbon dioxide exchange occurs on the ocean surface when phyto plankton absorb it in photosynthesis → carbon content will be transferred to the ocean floor when they die → oil and natural gas rigs will extract this as fossil fuel

Question 25

Why might organisms of the same species have differences?

Answer 25

Different genetic coding inherited from parents, this is known as genetic variation.

Also, characteristics can be influenced by the environment (spending time in the sun will make your skin darker).

Question 26

How many pairs of chromosomes does a human cell nucleus contain?

Answer 26

23

Question 27

What is coiled up to make chromosomes ‘arms’?

Answer 27

DNA molecules which control the development of characteristics.

Question 28

What are different versions of the same gene called (eg different eye colours)?

Answer 28

Alleles

Question 29

What is sexual reproduction?

Answer 29

When genetic information from two organisms is combined to produce offspring.

Question 30

What are gametes?

Answer 30

The female egg and male sperm

Question 31

How many chromosomes does each human gamete contain?

Answer 31

23

Question 32

What is Asexual reproduction?

Answer 32

When only one parent is necessary to produce offspring.

Question 33

Describe how cells multiply in the process of asexual reproduction (3 main steps)

Answer 33

1. X shaped chromosomes have two identical halves so each chromosome splits to form two sets of half chromosomes.
2. A membrane will form around each set.
3. The DNA replicates itself to form two identical cells with complete sets of X shaped chromosomes.

Question 34

What two ways can plants be cloned?

Answer 34

• Cuttings
• Tissue culture (a few plants are put in a growth medium with hormones that cause them to grow into new plants)

Question 35

How can famers clone animals? (3 main steps)

Answer 35

1. Sperm and egg cells are extracted from the two chosen animals.
2. They are artifically fertilised.
3. The embryo that develops is split many times in order to create clones that can be implanted into the female animals uterus.

Question 36

Describe the process of adult cell cloning and which famous animal was created this way?

Answer 36

• An unfertilised egg is extracted and its genetic material (the nucleus) is removed
• A complete set of chromosomes from an adult body cell is inserted and an electric shock stimulates fertilisation
• When the embryo develops it can be implanted into a surrogate mother

Dolly the Sheep was created by this process

Question 37

List the issues raised by cloning (3)

Answer 37

• Reduces gene pool (fewer different alleles and if a new disease appears the population could be wiped out because there is no allele to give resistance)
• Cloned animals might not be as healthy (eg. Dolly had arthritis)
• People worry about the prospect of humans being cloned in the future and whether cloning is ethical

Question 38

What are the advantages of cloning technology?

Answer 38

• “Ideal” offspring can be created
• Could preserve endangered species

Question 39

Describe how organisms can be genetically engineered (2 main steps)

Answer 39

A “useful” gene will be cut from one organism’s chromosome using enzymes.

Enzymes are then used to cut another organism’s chromosomes and insert the “useful” gene.

Question 40

Give an example of when genetic engineering has been beneficial to healthcare

Answer 40

Insulin treatment for diabetics:

The insulin gene from human DNA is inserted into the DNA of bacteria which are cultivated and prescribed to people suffering with diabetes.

Question 41

Why might crops be genetically modified?

Answer 41

To make them resistant to viruses, insects or herbicides

Question 42

How have sheep been genetically modified?

Answer 42

To produce substances like drugs in their milk than can be used to treat human diseases

Question 43

How are scientists trying to treat disorders with GM?

Answer 43

Genetic disorders like cystic fibrosis are caused by faulty genes. Scientists are trying to treat them by inserting working genes into humans. This is known as gene therapy.

Question 44

What are the arguments for genetically modifying crops? (3)

Answer 44

• Can increase yield
• Engineered to increase nutrients for people in developing countries who may be malnourished (eg. Golden Rice modified to contain beta-carotene - lack of this nutrient is a huge cause of blindness)
• GM crops are already being grown elsewhere in the world

Question 45

List three arguments against genetically modifying crops

Answer 45

• It will decrease the number of weeds, flowers and insects around crops and limit biodiversity
• Not everyone is convinced they are safe - allergies might develop
• Transplanted genes may enter the natural environment (eg. herbicide resistance may be picked up by weeds and create ‘superweeds’)

Question 46

Briefly describe the theory of evolution

Answer 46

All life on Earth began as simple organism, from which more complex organisms evolved in order to survive in their environment

Question 47

What are the main differences between plants, animals and bacteria?

Answer 47

Plants can make their own food by photosynthesis and are fixed in the ground

Animals move and cannot make their own food

Bacteria are single celled organisms

Question 48

What is Charles Darwin’s theory of natural selection? (3 main points)

Answer 48

• Individuals in species have variation due to different genes
• Those with genes whose characteristiccs make them better adapted to their environment are most likely to survive and reproduce
• The genes responsible for the successful characteristics are passed to the next generation

Question 49

How can mutations in DNA be useful?

Answer 49

Often they have no effect but occasionally they can be beneficial by producing a useful characteristic, that can be inherited by the next generation. An example of this is some strains of bacteria being resistant to antibiotics.

Question 50

What opposition did Charles Darwin face with regards to his theory of revolution and natural selection?

Answer 50

• Religious beliefs that the world and everything in it is created by God (creationism)
• He couldn’t explain why or how the useful characteristics appeared because science wasn’t so advanced that it could explain genes and mutation (weren’t discovered until 50 years after his theory was published)
• He didn’t have enough conclusive evidence because not enough studies had been carried out.

Question 51

What was Jean-Baptiste Lamarck’s reason for genetic variation?

Answer 51

He believed that if a characteristic was used a lot by an organism then it would develop further and become stronger over its lifetime (eg. Giraffe stretching it’s neck for food, caused it to become longer). And these characteristics would be passed to its offspring.

Question 52

Why was Lamarck’s hypothesis rejected?

Answer 52

Experiments didn’t support it and there was no genetic basis for his argument, the existence of genes is what provided the explanation necessary to prove Darwin’s hypothesis as a theory.