Variation And Genes

Question 1

What are the 2 types of variation

Answer 1

• genetic variation
• environmental variation

Question 2

What is genetic variation

Answer 2

• caused by differences in genotype
• which then affects it’s phenotype
• these differences are inherited

Question 3

What is environmental variation

Answer 3

• interactions with the environment having an influence on an organisms phenotype
• e.g. plant being yellow is it doesn’t photosynthesise properly

Question 4

What is a mutation

Answer 4

• rare,random change to DNA that can be inherited
• mutations occur continuously
• a gene becomes altered, producing a genetic variant

Question 5

What does mutation effect

Answer 5

• As the gene codes for the sequence of amino acids that make up a protein, gene mutations sometimes lead to changes in the protein that it codes for
• resulting on an influence on the organisms phenotype

Question 6

What is the theory of evolution

Answer 6

All of today’s species have evolved from simple life forms that first started to develop over 3 billion years ago

Question 7

How to answer a question about evolution/natural selection resulting non a higher population of mutated animals

Answer 7

• variation arises in population due to a mutation from reproduction
• The mutation gives the organism an advantage — more likely to survive
• Therefore they’re more likely to reproduce and pass on this gene
• overtime making it more common in the population

Question 8

What is speciation

Answer 8

• when phenotypes have changed so much that they become reproductively isolated from the original species

Question 9

Why might a species become extinct

Answer 9

• environmental changes (e.g. destruction of habitat)
• A new predator kills them all
• A new disease kills them all
• Can’t compete with another species for food
• A catastrophic event happens, killing them all (e.g. volcano)

Question 10

What is selective breeding

Answer 10

• humans artificially select plants or animals to breed for desired characteristics

Question 11

What are some examples of why we might selectively breed

Answer 11

• Animals to produce more meat or milk
• Crops with a resistance to disease
• Dogs with a good, gentle temperament
• decorative plants with big or unusual flowers

Question 12

Describe the process in selective breeding

Answer 12

• select organisms with the desired characteristics
• breed them
• select the best of the offspring, and continue breeding
• continue over several generations, making the characteristic stronger and stronger

Question 13

What is the draw back to selective breeding

Answer 13

• reduces gene pool
• can lead to inbreeding
  —> which leads to health problems
• reduction in number of different alleles, so a new disease can wipe them all out because there’s less chance of there being any resistant alleles

Question 14

What is genetic engineering

Answer 14

• transferring genes responsible for a desirable characteristic from one organism to another, so that it has the desirable;e characteristic

Question 15

Describe the process of genetic engineering

Answer 15

• useful gene is isolated from one organism’s genome using enzymes and is inserted into a vector
• the vector is usually a virus or bacterial plasmid (depending on the organsim it’s transferring to)
• when the vector is introduced to the target organism, the useful gene is inserted into its cells
• the organism then develops with desired characteristic, coded for by the gene

Question 16

What are some of the worries with genetic engineering

Answer 16

• accidentally create unplanned problems which get passed onto future generations

Question 17

What are the pros to genetic modification

Answer 17

• increases yield for crops = more food
• helps people who lack nutrients in developing nations
• is already being used for crops in some places without any problems

Question 18

What are the cons to genetic modification

Answer 18

• can affect the No. of wild flowers and insects that live in crops — reducing farmland biodiversity
• we don’t fully understand side effects to eating GM crops
• herbicide resistant may get picked up by naturally occurring weeds from GM crops, creating super weed

Question 19

What are the 3 ways fossils will form

Answer 19

• From gradual replacement by minerals
• From casts and impressions
• From Preservation in place where no decay happens

Question 20

How are fossils formed from gradual replacement by minerals

Answer 20

• Things like teeth, shells and bones that don’t decay easily, are buried
• eventually they are replaced by minerals when they decay, forming a rock-like substance, shaped like the OG
• surrounding sediment also turns to rock, but fossil stays distinct inside the rock

Question 21

How are fossils formed form casts and impressions

Answer 21

• organisms buried in soft clay
• it hardens around organism and the organisms decays. Leaving a cast
• impressions form when things like footprints are pressed into theses soft materials

Question 22

How are fossils formed from preservations in places where no decay happens

Answer 22

• in amber and tar pits, there’s no oxygen or moisture = decay microbes can’t survive
• In glaciers, it’s too cold = decay microbes can’t survive
• In peat bogs, it’s too acidic = decay microbes can’t survive

Question 23

Why can’t we tell how life began

Answer 23

• lack of evidence
• soft bodied animals decays too quickly to be fossilised
• some important fossils might’ve been destroyed by geological activity

Question 24

What is classification

Answer 24

• By Carl Linnaeus in 1700s
• groups living things according to their characteristics and the structures that make them up

Question 25

What are the different groups in classification

Answer 25

• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species

Question 26

What’s the pneumonic to remember the different groups of dividing organisms

Answer 26

Keep pond clean or frogs get sick

Question 27

Why has classification improved over time

Answer 27

• microscopes improved = more knowledge of biochemical processes
• Carl Woese proposed 3 domain system

Question 28

Explain the 3 groups in the 3 domain system

Answer 28

• ARCHAEA: primitive bacteria, found in extreme places (e.g. hot springs or salt lakes)
• BACTERIA: true bacteria (e.g. E.coli). The have biochemical differences to archaea
• EUKARYOTA: fungi, plants, animals, protists

Question 29

Explain how the Binomial system works

Answer 29

• two part Latin name
• first part: Genus with capital letter
• second part: Species
• e.g. Homo Sapiens