Unit 1B - Environmnet and Evolution

Question 1

How have animals living in the desert adapted to survive better?

Answer 1

Large SA:V ratio - Allows them to lose more body heat
Efficient with water - Lose less water through urine by increasing concentration and also sweat very little
Good in hot conditions - They have very thin layers of fat and a thin coat to maximise heat loss
Camouflage - A sandy colour allows them to avoid predators or sneak up on prey

Question 2

How have arctic animals adapted to survive better?

Answer 2

Small SA:V ratio - This minimises heat loss
Well insulated - They have a thick layer of blubber for insulation and also acts as a food source when food is scarce, thick hair coats that keep body heat in and greasy fur that sheds water which prevents cooling due to evaporation
Camouflage - They have white fur to make them inconspicuous to prey or predators

Question 3

How have desert plants adapted to their environment?

Answer 3

Small SA:V ratio - Plants lose water vapour from the surface of their leaves cacti have spines instead to reduce water loss
Water storage tissues - eg. Cacti store water in their thick stem
Maximise water absorption - some cacti have shallow but extensive roots to absorb water quickly over a large area some have deep roots to access underground water

Question 4

Who have plants and animals adapted to deter predators?

Answer 4

Armour - Roses thorns, Cacti spines, Tortoises shells
Poisons - Bees and poison ivy
Warning colours - Wasps

Question 5

What is the name given to microorganisms that can survive in extreme conditions and give examples of these conditions

Answer 5

Extremophiles
Hot volcanic vents
Very salty lakes
High pressures on the sea bed

Question 6

What do plants compete for?

Answer 6

Light
Space
Water
Minerals (nutrients)

Question 7

What do animals compete for?

Answer 7

Space (territory)
Food
Water
Mates

Question 8

What living factors could change where an organism lives?

Answer 8

Disease
Increase/new predators
Less prey/food sources
Increase in competitors

Question 9

What non living factors could change where an organism lives?

Answer 9

Change in temperature
Change in rainfall
Increase in air/water pollution

Question 10

How does environmental changes affect populations?

Answer 10

Population increases
Population decreases
Population distribution changes

Question 11

What is the name given to organisms that are studied to see the effect of human activities?

Answer 11

Indicator species

Question 12

How is air pollution monitored?

Answer 12

Lichen used to measure sulfur dioxide levels, if there are a lot of lichen then the air is clean

Question 13

How are water pollution levels monitored?

Answer 13

Some invertebrate animals such as mayfly larvae decrease when the concentration of dissolved oxygen in the water is too low. This will be because bacteria from raw sewage are using it up.

Also rat tailed maggots and sludgeworms have adapted to live in polluted conditions so when there is a high number of them then the water is polluted

Question 14

What non living indicators are used to monitor environmental change?

Answer 14

Satellites - used to measure temperature of the sea surface
Automatic weather stations - measure atmospheric temperatures at different locations
Rain gauges - measure rainfall
Dissolved oxygen metres - used to measure dissolved oxygen in water

Question 15

What trend do all pyramids of biomass follow as you move up the trophies levels?

Answer 15

There is less energy and biomass

Question 16

What does each bar represent on pyramids of biomass?

Answer 16

The mass of living material at that stage (biomass)

Question 17

How is energy lost in biomass pyramids?

Answer 17

Respiration (movement) energy is used to keep the organism alive and functioning
Energy is used to regulate body temperatures
Some of the organism is inedible eg. Bones
Material and energy is lost through waste material

Question 18

Why is it unlikely to get food chains with more than five tropic levels?

Answer 18

There is not enough energy left to support another organism

Question 19

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

Answer 19

Waste products and dead organisms decay into the soil returning the solis original nutrients
Decay occurs due to microorganisms, they work best in warm, moist conditions that have plenty of oxygen
These elements are then absorbed by plants and go back through the food chain

Question 20

How does the carbon cycle work?

Answer 20

Carbon dioxide is absorbed by plants for photosynthesis
Some goes back into the atmosphere when the plants respire
Plants are either:
Eaten by animals that respire, releasing CO2 or die and decay into the soil.
CO2 is released when decaying occurs as the microorganisms respire
Some of the carbon is absorbed into the soil and becomes fossil fuels which when burnt releases CO2
Or
Products are made from plants and animals like wood and clothes and burning is required which releases CO2

Question 21

Why do organisms in the same species look different?

Answer 21

Variation

Question 22

What are the two types of variation?

Answer 22

Genetic variation

Environmental variation

Question 23

What causes genetic variation and how?

Answer 23

Different genes

The combination of genes from two parents cause this

Question 24

Name three examples of characteristics determined only by genes

Answer 24

Eye colour
Blood type
Inherited disorders

Question 25

What causes environmental variation?

Answer 25

The environment

Question 26

How does the genetic information work in humans?

Answer 26

Most cells contain a nucleus
The nucleus contains 23 pairs of chromosomes
The chromosomes carry genes
Genes control the development of different characteristics
DNA makes up the genes

Question 27

What are the two ways of reproducing?

Answer 27

Sexual reproduction

Asexual reproduction

Question 28

How does sexual reproduction work?

Answer 28

Two organisms (male and female) are required
The sex gametes from each individual fuse together to form a cell with 23 pairs of chromosomes half from the mother half from the father
The mixture of the genetic material produces variation

Question 29

How does asexual reproduction work?

Answer 29

On,y one parent is involved there is no fusion of gametes, no mixing of gametes and no genetic variation between the parent and the offspring they are genetically identical
It works by mitosis

Question 30

Who can plants be cloned?

Answer 30

They can be cloned from cuttings and tissue culture

Question 31

How does cuttings work?

Answer 31

Gardeners take cuttings from a good parent plant and then plant them to produce identical copies.
They are kept in moist and warm conditions until they are ready to be planted by covering them in a clear plastic bag
Plant hormones are used to stimulate growth
They are produced quickly and cheaply

Question 32

How does tissue culture work?

Answer 32

Plant tissue is removed from the parent plant
The tissue is placed in sterile agar jelly with the correct conditions needed to maximise plant growth
The cells divide and grow rapidly until they develop stems and roots where they are planted in potting trays and develop into clone plants
These plants can be made very quickly with little space but cost more money

Question 33

How do embryo transplants work?

Answer 33

Sperm is taken from a prize bulb and the egg from a prize cow
They are fertilised outside the body of the cow and once an embryo it is formed is split many times into small cluster of cells before any of the cells become specialised
These cells then develop into identical embryos which are implanted into surrogate mothers and are born as clones of each other

Question 34

How does adult cell cloning work?

Answer 34

The nucleus from a female egg cell is removed and is replaced with the nucleus from an adult body cell of the animal that is being cloned
The cell is then given an electric shock to get it to to start dividing and to form an embryo
The embryo is then implanted into a surrogate mother and a clone is born

Question 35

What are the issues of cloning?

Answer 35

Cloning means there is a reduced gene pool which means that a population could easily be wiped out by a disease as none of them will be immune to it as they are all the same
People worry that humans might be cloned
Cloned animals may not be a healthy, dolly the sheep had arthritis

Question 36

What are the benefits of cloning?

Answer 36

Studying clones can help develop understanding of embryos, ageing and age related disorders
Can help preserve endangered species
More food from prize cows

Question 37

How does genetic engineering work?

Answer 37

An enzyme is used to cut a useful game from an organism
Another enzyme is then used to cut another organisms chromosome and insert the gene into it
This is useful for the production of insulin as it is inserted in bacteria and they reproduce rapidly so more human insulin is produced

Question 38

What are GM crops?

Answer 38

Crops that have had their genes altered to make them resistant to viruses, insects or herbicides for example

Question 39

What is gene therapy?

Answer 39

This is where genetic disorders are countered by inserting working genes into suffers eg. People with cystic fibrosis

Question 40

What are the possibilities of genetic engineering and why are some people opposed to it?

Answer 40

Can be used to treat disease, more efficient food production etc.
People are worried about the long term effects and the chance of unplanned problems occurring that are then passed onto future generations

Question 41

What are the pros and cons of GM crops?

Answer 41

Some people say they will affect the number of weeds and flowers and will reduce farmland biodiversity
Worries about being allergic to the crops and that they’re not safe to eat
Possibility of transplanted genes getting out into the environment eg. Resistance to herbicides could be picked up by a weed species creating a super weed
However they can increase the yield of food
They can have nutrients added that people in developing countries are lacking
They are already being grown elsewhere in the world and there have been no problems

Question 42

What is theory of evolution?

Answer 42

More than 3 billion years ago, life on Earth began as simple organisms from which all the more complex organisms evolved.

Question 43

How does natural selection work and who came up with it?

Answer 43

Charles Darwin
Individuals in species show variation due to differences in their genes
Individuals that have characteristics that make them better adapted have a higher chance of surviving for longer and therefore reproducing more
The genes are then likely to be passed onto the next generation, increasing the proportion of the population that has the gene this repeats until most of the species possesses the gene

Question 44

Why was Darwin’s theory initially rejected?

Answer 44

It went against religious beliefs
Darwin could not provide a good explanation for why these new characteristics appeared
There was not enough evidence to convince many scientists

Question 45

Who was the Lamark and what was his theory?

Answer 45

Lamark came up with the theory that acquired characteristics would be passed on to the next generation for example a rabbit that use its legs to run a lot would produce offspring that had longer legs

Question 46

What happened to Lanark’s theory and Darwin theory?

Answer 46

Lamarks hypothesis was rejected as scientists could prove it was incorrect however there is a lot of evidence to support Darwin’s theory therefore it is widely excepted today