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Biology > B6.2 > Flashcards

B6.2 Flashcards

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1
Q

What is food security?

A

The ability of human populations to access affordable food of sufficient quality and quantity

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2
Q

What factors affect food security?

A

Increasing human population
Changing diets - more meat in energy intensive
Climate change - more droughts but high carbon dioxide also means increased yields of crops
New pests and pathogens may evolve
Agricultural costs and oil prices - increase food prices

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3
Q

What can we do to maintain food production?

A

Maximise photosynthesis
Use fertilisers
Remove competition and pests
Plant crops that are pests resistant or produce a higher yield

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4
Q

How can we maximise photosynthesis?

A

Use an industrial glasshouse to control:
Light levels
Temperature
Water

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5
Q

How do fertilisers increase food production?

A

As a plant grows, minerals are lost from the soil and fertilisers help keep the land fertile

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6
Q

What is intensive farming?

A

Farming that aims to produce the maximum food product yield from the minimum area of land

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7
Q

What are examples of intensive farming?

A

Use fertilisers and pesticides to aid plant growth
Maximising animal growth rates
Minimising labour inputs by using machinery

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8
Q

How can one maximise animal growth rates?

A

Make the animal restricted from movement so it can use its energy from growth instradb

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9
Q

What is organic farming?

A

Farming which uses more natural methods of producing crops and rearing animals - avoids artificial chemicals

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10
Q

What is bad about organic farming?

A

Yields are generally smaller, so products tend to be more expensive

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11
Q

What is sustainable food production?

A

Producing food in ways that can be continued indefinitely - e.g fish farming

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12
Q

How is fish farming sustainable?

A

Organisation have introduced fishing quotas which provide limits on the numbers and types of fish caught.
Also, nets sizes are bigger so only mature fish can be caught and small fish can escape

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13
Q

What is good about fish farming?

A

Fish are bred and reared in large cages in the sea or rivers so it:
Protects fish from predators
Makes fish easier to catch
Allows wild populations to recover

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14
Q

What is bad about fish farming?

A

Disease can spread easily as they are so close together

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15
Q

What have international organisations done to prevent overfishing?

A

Introduce fishing quotas:
Limit the numbers and types of fish caught in an area
Limit the mesh size of nets

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16
Q

Why are the mesh sizes of nets regulated?

A

They are regulated to be bigger as bigger holes mean only mature, full-sized fish are caught so young fish can escape

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17
Q

How can farmers reduce the use of fertilisers and pesticides?

A

Replace soil nutrients by spreading manure
Crop rotation
Biological control

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18
Q

What is crop rotation?

A

Different crops take different nutrients from the soil - planing different crops each year

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19
Q

What are the advantages of crop rotation?

A

Gives soil a chance to recover
Maximises plant growth
Prevents the buildup of a particular crop pest

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20
Q

What is biological control?

A

When predators are bred in large number to eat the pests that eat the crops

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21
Q

Why might pesticides be bad?

A

They can damage other organisms

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22
Q

What is hydroponics?

A

A system in which plants are grown in water containing dissolved minerals

23
Q

What is good about hydroponics?

A

It ensures that a plant can get all the minerals that it needs

24
Q

What is selective breeding?

A

When you breed animals and plants for particular characteristics

25
Q

What are the 5 steps for selectively breeding organisms?

A

Decide which characteristic is desirable
Select parents with high levels of this characteristic
Breed these organisms
Select the best offspring and breed again
Repeat for generations

26
Q

How has selective breeding changed wheat?

A

Wild Wheat plants - small ears with few seeds, brittle stalks with ears that fall off, ears ripen at different times, stalks have different heights

Modern wheat - large ears with many seeds, stronger stalks that ears stay on, ears ripen at the same time, stalks grow to the same height

27
Q

What are the disadvantages of selective breeding?

A

Reduces the number of alleles which reduces variation
Increased chance of inheriting a genetic disease

28
Q

Why is reduced variation bad?

A

If a new disease emerges, there may not be an organism with an allele for resistance against this disease - may become extinct

29
Q

In what ways is generic engineering better than selective breeding?

A

Genetic breeding is faster and more accurate

30
Q

What is genetic engineering?

A

When you take a desired gene from one organism and put it in a different organism to gain the characteristic of the gene

31
Q

What are positive examples of genetic engineering?

A

Cotton - increase crop yield in the same area of land
Corn - making the plant pest resistant by producing a toxin that kill pests - less pesticide needed
Bacteria - to produce medical drugs such as insulin or to treat diseases

32
Q

What are foreign genes?

A

Genes taken from another organism that code for a desired characteristic

33
Q

What is a transgenic organism?

A

An organism that carries the genes of one or more other organism

34
Q

When are foreign genes usually implanted into an organism?

A

During the early stage of development

35
Q

Why are foreign genes implanted at an early stage of development?

A

As the organism develops, it displays the characteristics coded by the foreign genes - can replicate and integrate with every cell in the organism

36
Q

What are some disadvantages of genetic engineering?

A

Eating genetically engineered organisms can lead to health problems
Genetically engineered crops can crops-pollinate
Some people don’t like the idea of eating genetically engineered food - unethical

37
Q

How can generic engineering cause health problems?

A

When eating the genetically modified organism, it can introduce new allergens that can cause some people to be allergic to the organism

38
Q

Why is cross-pollinating with wild plants bad?

A

It can introduce a new gene into wild plants and disrupt the balance of an ecosystem

39
Q

Why might generic engineering be classed as unethical?

A

Altering with an organism’s genome is seen as science interfering with nature

40
Q

How does one find the required gene in an an organism?

A

Use enzymes

41
Q

How do you genetically engineer bacteria?

A
  1. Use an enzyme to find the required gene
  2. Use the reverse transcriptase enzyme to reverse transcribe the DNA and use DNA polymerase to make another single strand of the DNA strand needed to give a gene.
  3. Use restriction enzymes to cut some sticky ends onto the DNA strand.
  4. Use ligase enzymes to rejoin DNA strands at the sticky ends
  5. Put the gene into a PCR machine to multiply the gene
  6. Cells with desired enzyme identified and cloned
42
Q

What 2 things do restrictions enzymes do?

A
  1. Cut donor DNA at specific base sequences (either side of the desired gene) - make a staggered cut leaving sticky ends.
  2. Also see to cut bacterial plasmid
43
Q

What are sticky ends?

A

A few exposed unpaired bases on the ends of the DNA strand

44
Q

What is a bacterial plasmid?

A

A loop of DNA that is separate from chromosomal DNA and is able to replicate separately

45
Q

What do Ligase enzymes do?

A

They rejoin DNA strands at the sticky ends - both the host and donor DNA have the same sticky ends so the gene is joined into the plasmid DNA.

46
Q

What is the difference between cloning and genetic engineering?

A

Cloning - produces exact genetic copies, genes copied within same species
Genetic engineering - produces a unique set of genes and the genes are transferred between species

47
Q

How can scientists check that the gene has successfully transferred into the host’s genome?

A

They add a gene for antibiotic resistance - a gene marker

48
Q

How does adding a gene marker work?

A
  1. Insert the antibiotic gene into the plasmid at the same time as putting in the desired gene.
  2. Transfer the bacteria into an agar plate which has the antibiotic in it and incubate
  3. All the bacterial colonies should survive as they have the desired gene but some will die, leaving us with only the bacteria that have the desired gene
49
Q

How do you genetically modify bacteria?

A
  1. The required gene is cut from the rest of DNA by restriction enzymes
  2. A plasmid is removed from the bacterial cell
  3. The plasmid is cut open using the same restriction enzymes as the ones used to cut the required gene from the DNA.
  4. The human gene sticky ends and the plasmid sticky ends are joined together by ligase enzymes
  5. This new loop of DNA (vector) is inserted into a new bacterium
  6. The bacteria are called transgenic and are grown in large numbers
50
Q

What is a vector?

A

Anything used to transfer foreign DNA into an organism

51
Q

What is genetic modification?

A

Genetic engineering but is used when referring to plants and animals

52
Q

What are 2 examples of GM crops?

A

Golden rice - gene take from a daffodil into rice to make the rice produce more beta-carotene (Vitamin A) to help eyesight.
Bt corn - inserting a gene into maize from the bacteria bacillus thuringiensis which codes for a protein that kills insect pests

53
Q

How do you genetically modify an organism?

A
  1. Required gene is cut out of a plant/organism using restriction enzymes
  2. DNA of a vector is cut out using the same restriction enzymes
  3. The useful gene is spliced into the DNA of the vector
  4. This vector is injected into a plant (insertion)
  5. The new gene begins to work
  6. The GM organism is cloned, producing many organisms with the required gene
54
Q

What is the formula for percentage change?

A

(Final value - initial value)
—————————————x 100
Initial value

Biology (8 decks)

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