variation and evolution

Question 1

classification

Answer 1

placing objects into groups based on similar characteristics

Question 2

taxonomy

Answer 2

science of classifying organisms

Question 3

species

Answer 3

a group of similar organisms that are capable of naturally interbreeding with each other to produce fertile offspring

Question 4

variation within a species

Answer 4

in a group of successfully interbreeding organisms the individual members show different characteristics

Question 5

inherited variation

Answer 5

controlled by genes i.e hair colour

Question 6

acquired variation

Answer 6

not inherited but learned or developed during life i.e ability to ride a bike

Question 7

give three causes of variation by sexual means

Answer 7

-independent assortment of chromosomes during meiosis
-crossing over during meiosis allows -genes to be exchanged between chromosomes
-random assortment of chromosomes in egg and sperm allows for variation when they join at fertilisation

Question 8

mutation

Answer 8

spontaneous change in amounts or structure of dna

Question 9

mutagens

Answer 9

agents that cause mutations

Question 10

spontaneous mutations

Answer 10

dna fails to repair properly

Question 11

three mutagens

Answer 11

-some viruses
-chemicals like formaldehyde, caffeine, pesticide, tobacco smoke
-ionizing radiation like uv rays, gamma rays, x rays

Question 12

gene mutation

Answer 12

change in a single gene caused by changes in a single pair of bases

Question 13

example of gene mutation and how it arises

Answer 13

sickle cell anaemia
if a person has two copies of the mutated haemoglobin gene the red blood cells formed will be curved.
this leads to blood clumping and breakdown leading to paleness heart failure and death
a treatment is blood transfusion

Question 14

chromosome mutation

Answer 14

change in the number or structure of one or more chromosomes

Question 15

explain how a chromosome mutation arises

Answer 15

down syndrome a chromosome mutation occurs when a homologous chromosome fails to separate and so 2 of the haploid gametes are left with no number 21 chromosome and 2 are left with 2 number 21 chromosomes
effects include round face, small hands, almond eyes

Question 16

evolution

Answer 16

genetic changes in populations in reesponse to environmental conditions

Question 17

who developed the theory of natural selection

Answer 17

charles darwin and alfred russell wallace

Question 18

theory 1: population numbers remain constant

Answer 18

number of organisms of species increases until environment can no longer support then the number of organisms stays the same.

Question 19

theory 2:overbreeding

Answer 19

organisms produce a large number of offspring

Question 20

conclusion 1:struggle for existance

Answer 20

due to the overbreeding the environment cannot handle all the organisms hence competition exists. Organisms compete for scarce resources like food

Question 21

observation 3:inherited variations occur in populations

Answer 21

inherited differences may arise due to sexual reproduction, mutations or genetic engineering

Question 22

conclusion 2: natural selection

Answer 22

ultimately known as survival of the fittest. Organisms develop variations allowing for better adaption. These organisms survive reproduce and pass the variations to offspring.

Question 23

natural selection

Answer 23

process by which those organisms with gentically controlled characteristics that allow them to be well adapted to their environments will survive reproduce and pass there genes onto to next generations

Question 24

speciation

Answer 24

the production of new species as a result of evolution

Question 25

examples of evolution

Answer 25

-bacteria are becoming more resistant to antibiotics -the black peppered moth became dominant over the normal lichen moth during the industrial revolution

Question 26

fossils

Answer 26

remains or indication of something that lived a long time ago

Question 27

how do fossils prove evolution

Answer 27

-there are fewer types of fossils from older eras i.e less variation -modern fossils are more complex their structures have changed over time -many fossil organisms are not found today like dodo -present day organisms have no fossils