Inheritance, Variation And Evlolution 🏔 Flashcards
1
Q
What are the two types of cell division?
A
Mitosis- asexual
meiosis- sexual
2
Q
How does meiosis occur + what does it require?
A
The sperm fuses with the egg (fertilisation)
Forming a zygote
Within the zygote, the genetic material duplicates
They line up and get pulled apart by cell fibres
causing the nucleus to divide in two
A second diffusion occurs
This leads to 4 genetically different sex cells being formed
Requires a mum and dad
3
Q
What does mitosis require + produce?
A
1 parent
Only 1 cell division
No gamete fusion (asexual)
Offspring are clones (identical daughter cells)
4
Q
What happens as soon as the embryo reaches a certain size in sexual reproduction?
A
Cells start to specialise
5
Q
Advantages of sexual reproduction?
A
Artificial selection eg selective breeding
Variation of offspring - higher survival rate due to being able to adapt to changes in environment
6
Q
Advantages of asexual reproduction ?
A
Lots of identical offspring is conditions a favourable
No mate
Faster
7
Q
What makes a chromosome ?
A
Coil of DNA makes of genes
8
Q
What does the genome sequencing help us understand?
A
Inherited disorders/how it can be treated
Gene identification
Human migratory history
9
Q
What is DNA
A
a polymer (covalently bonded)made up of a double helix
10
Q
What are the genes code made up of ?
A
Amino acids for specific proteins
11
Q
What is the genome sequence made up of?
A
Chromosome
DNA
gene
12
Q
What is a nucleotide made up of? What does T pair up with and what does G
A
Phosphate sugar and base
T-A
G-C
13
Q
What are protiens ?
A
Polymers of amino acids
14
Q
How many protiens are in humans ?
A
23
15
Q
What does the order of the amino acids (sequence of bases) in the protein determine ?
A
The shape and function of the protein
16
Q
What is the first stage of protein synthesis?
A
1.transcription occurs in nucleus - base sequence is copies into a complementary template called MRNA (single stranded molecule)
17
Q
What is the second stage of protein synthesis?
A
MRNA passes through the nucleus into the cytoplasm TRANSLATION
MRNA molecule attaches to a ribosome
Amino acids attaches to ribosome on carrier molecules TRNA
Ribosome connects TRNA in right order
Once complete, the protein chain folds in its unique shape enabling it to do its job .
18
Q
How many base codes are there?
A
3 (triplets)
19
Q
What happened if a code
uncomplementary Changes in a protein chain? What does it lead to the active state becoming?
A
Mutation occurs resulting in a change in protein shape leading to an active site being no longer complementary to substate
20
Q
What happens if a protein mutates at the wrong time ?
A
Uncontrolled mitosis leading to cancer
21
Q
What is non-coding DNA?
A
DNA that does not encode protein sequences
22
Q
What is cystic fibrosis?
What disorder is it?
A
An inherited disorder of a large build up of mucus in the lungs
Disorder of cell membranes
23
Q
Advantages of embryo screening?
A
Financial saving of medical bills
Prevent suffering from genetic orders
Able to view future implications
24
Q
What type of screening is embryo screening?
A
Genome
25
Disadvantages of embryo screening
Course cause discrimination
Expensive
Injustice (selective parents)
Unused embryos destroyed- unethical- killing human life
26
What are the men / woman genes
XY-men
Women-XX
27
How does selective breading take place
Pick 2 to be parents
Bred them
Pick offspring
Bread them
Carry on until appearance desires are met
28
What do selective breeders have to make sure? Why?
No unhealthy interbreeds
If so, could cause inheritary diseases
29
What is Darwin’s approach on natural selection?
1. Genetic variation
(different genes are within the population)
2. Survival of the fittest ( alleles are favourable )
3. Successful breading (favourable genes gets passed down to offspring)
4. Best characterises survive
30
Criticisms of Darwin?
1. Genes not discover
2. Evidence was inconclusive
3. Went against Christianity that god created the world
31
What was Lamark’s INCORRECT idea of evolution ? Why was he wrong?
Baby Giraffes gained their long neck characteristics but stretching it to eatleaves form trees, rather than it being a genetic feature this then gets passed on to offspring
THIS IS WRONG because changes of An animals lifetime do not get passes on to future generations.
32
What’s are the monomers that build up DNA called?
Nucleotides
33
How can a mutation in a gene result in a protein not carrying out its role correctly?
Mutation may carry a code for a different amino acid
Which could alter the structure of the Protein
Making it the wrong shape to transport water
34
What are fossils ?
Remains of organisms from millions of years ago found in rocks
35
When are the 3 ways that fossils can be formed ? + Examples?
1. When parts of an organism have not decayed e.g temp too cold not enough oxygen or water
2. When part of an organism has decayed if the parts of the organism is replaced by minerals
3. Preserves traces of organisms eg. Footprint
36
What were some problems of older organisms forming into skeletons ?
What does it lead to scientist thinking?
Where soft bodies - no skeletons
So rarely formed fossils
If it did , they were crushed by the earth’s crust
This makes scientist unable to know how life on earth started
37
What are the 4 ways species can become extinct?
1. Catastrophic event eg. Astroid
2.environmental changes eg. Change of weather patterns
3. New disease or new predator
4. New successful species evolve and competes with it for food or water
38
How many minutes can bacteria reproduce?
Why can bacteria evolve rapidly?
Every 30 minutes
They can evolve rapidly as the reproduce at a fast rate.
39
What antibiotic was first created ?
Penicillin
40
What is one common antibiotic strain of resistant bacteria?
MRSA
41
How do antibiotic resistant bacteria form ?
Why does the resistant strain spread?
1. Genetic variation takes place , some bacterias have favourable genes due to mutations
2. All bacteriums are killed except for the resistant one causing it to reproduce by mitosis with no competition
3. This causes the resistant bacteria population to rise
4. The resistant stain now spreads as people are not immune to it and no effective treatment
42
How can we reduce the amount of antibiotic resistant bacteria? (3 ways )
1. Doctors show not prescribe unnecessary antibiotic inappropriately as they have no effect
2. Patients need to complete the whole course of antibiotics making sure all bacterias have been killed and none have survived to mutate and form resistant strains
3. Reduce the use of antibiotics in farming
43
What are the negative of scientists developing new antibiotics?
Takes too long + expensive
Unlikely to keep up as new bacterias emerge all the time
44
Apart from genes , what are the two main sources of evidence from evolution
Fossils
antibiotic resistant bacteria
45
What is a gene?
A section is DNA on a chromosome
46
How did Mendel investigate inheritance? What did he find out?
Did breeding experiments on pea plants That characteristics were not blended during inheritance
47
What did Mendel say characteristics are determined by? What else sis he found out a lot characteristics?
By inherited units (genes) which do not change when passed in to descendants.
He found out that characteristics can be masked and then reappear in future generations (recessive)
48
Give an example of a slow extinction and a rapid one
Slow - atmospherical
Fast- catastrophic event eg volcanic eruption
49
What did Mendel experiment on? What helped him support his work?
Pea plants
Discovery of chromosomes
DNA discovered in 20th century
50
What is a stabilising selection?
What kind of environment is it in?
Natural selection that favours an average phenotype in environment that do not change
51
Directional selection?
Selection that favoured an extra am phenotype eg. Mutation
Happend aster a change in environment
52
What are the two kingdoms Linnaeus split species in?
Plant and Animal kingdom
53
What is the order of the kingdoms?
Kick
Poo
Cat
On
Fat
Geese
Sorry
Kingdom
Phylum
Class
Order
Family
Genus
Species
54
What is the binomial name ?
What is the classing system based on ?
Genus and species
Appearance of animals
55
What it’s the three domain system ? Who invented it? What does it intel?
Woese
comparing the biochemistry between 2 organisms
1. Primitive bacteria- extremophiles eg. Archae found Extrems conditions
2. True bacteria found in human digestive system
3. Eukaryota - animal, plant, protists
56
Problems with evolutionary trees?
Cannot plot old species as fossil data is incomplete
57
How do we investigate decay?
What are the two catalysts added?
1. Label test tube lipase and put 5 cm of lipase solution in
2. do the same to a new tests tube labels milk and add 5 drops cresol red using a Pipette then add 5cm^3 of milk and sodium carbonate
3. Solution turns purple because sodium
Carbonate is a alkaline
4.place thermometer in milk the place both test tubes in a water bath at ur initial temp 20
5. Wait until temp of both test tubes then transferred lipase (catalyst) to the milk and stir + time
6. Lipase starts to break down molecules in the milk releasing fatty acids causing the milk to be acidic turning the milk yellow
5. Repeat at different temps
58
What is the independent
Dependent
And control variables in the decay practical?
Independent- temp
Dependent- time taken for milk to turn yellow
Control-vol Of solution
59
What do scientist have to avoid during the decay practical?
Dirty test tube will trigger the reaction before we are ready.
60
State the foods chain
Producer - grass
Primary consumer - caterpillar
Secondary consumer - bird
Tertiary consumer - fox
61
What is a biomass ?
The mass of a all organisms in a population
62
What is the dry biomass ? Why is it’s good
Killing spices and drying them out this is
good as water content in each creature varies so it’s more accurate
63
How many levels are there in a biomass pyramid?
What kind of organisms are on each level?
What % of light every is used for photosynthesis?
4
3
2
1- plants that carry out photosynthesis
only 1% of light energy is used in photosynthesis
64
What is a biomass? (Def 2)
Living tissues of organisms including proteins lipids and carbs
65
If an biomass is eaten why is only 1% absorbed ?
Some egested as feaces
Not all biomass is absorbed
Absorbed biomass is converted as waste Products of metabolic reactions and released eg urea
Biomass is used up for respiration to release energy and movement
Aerobic- carbon dioxide and water
66
What happens during embryos embryos screening?
And alleles tested to see if they have any inherited alleles for inherited disorders
67
What are scientists going to be able to do in the future with Embryos ?
May be able to correct Faulty alleles inherited disorders
68
How do you know cystic fibrosis is recessive on a family tree
Person 11 does have cystic fibrosis However person seven or eight have cystic fibrosis
This means that the person 7 and 8 have to be carriers or cystic fibrosis and they are you must be recessive
If cystic fibrosis has a dominant allele at least one of the parents had to have cystic fibrosis in order to carry it to person 11
69
What is heterozygous
Two different alleles so one dominant and recessive
70
What is homozygous?
Two of the same alleles so two recessive or two dominant
71
What is the genotype for somebody who has polydactyl?
Pp
72
What is variation
The difference in the characteristics of individuals in a population
73
What are the three main causes of variation?
Alleles that individuals have inherited- genetic causes - Phenotype hair colour eye colour
Environment-Colour of flowers depends on pH of the soil We are humans talk language accent
Genes and the environment- height - genetic tall alleles but diet needs lots of calcium for bones 🦴 to fully developed
74
What makes genetic variation?
Mutations- Random changes to DNA
75
What mutations have no effect at all on?
Phenotype but can Influencer Are you into this may lead to a person if the diet is suitable
76
What can mutations lead to?
New Phenotype
77
Why may mutations be useful?
Changing phenotypes may lead to benefit in environmental changes which can lead to rapid change in species
78
When do scientists believe in life developed on earth?
3 bill years ago- simple single cells
79
What is animals evolving called ?
Evolution by natural selection
80
Explain natural selection
And three species every specie will have a combination of alleles that is inherited from parents
Some may have better alleles for better hearing or seeing or thicker fur
If the environment changes into colder climates rabbits with thicker fur will survive and going to reproduce passing on the favourable alleles to future generations
At the time the whole population will have thicker fur than before

81
What is evolution
The change of the inherited characteristics of a population over time do the process of natural selection
82
What happens if one species Become so different with phenotypes?
They can no longer interbreed and reproduce fertile offspring-They’ve become two separate species
83
What are the four kinds of Selective breeding we have to know
Domestic dogs have been selectively bred to have a gentle nature
Food Crop to be resistant to disease
Cows to produce more meat or milk
Plants to produce large or unusual flowers
84
Explain selective breeding for cows
We get a mixed population and get the largest female and male
Breed
We know sexual reproduction produces variation in Offspring
Get the largest melon female breed them to get them continue doing over many generations this until all of springs are large
85
What are the issues with selective breeding
If we keep on selectively breeding closely related animals we may lead to inbreeding
Causing some animals to be prone to disease or inherited defects
86
What is genetic engineering
We get a gene from a human and we cut it out and transfer it into bacteria
The genome of the bacteria is modified and now includes a human gene
Could be insulin
This bacteria now produces insulin which can be purified and used for type one diabetes
87
How else can we use genes in plants to produce..?
Genetically modified crops produce larger yield and are resistant to disease or insect attack
Produce larger and better fruits
Resistance to weed killers
88
What are the issues with genetically modified crops
People believe it may damage ecosystems or insects
and there are health effects eating 🍽 them 
89
Why is genetherapy a controversial topic?
We don’t know how will have an effect on other genes within the embryo
90
Explain the genetic engineering process
We identify the Gene we want to transfer
We use enzymes to isolate this gene
We transferred into plasmid- They are vectors because they transfer genes from one organism to another
The desired genes are transferred into the target organism

91
What is the key facts with genetic engineering?
We always transfer the gene at an early stage in the organisms development
Embryo to make sure that all the cells receive the transferred Gene
So organism develops with the characteristics we want
92
What is one big Advantage of cloning a plant
We know its exact characteristics
93
How can we clone a plant (small)
Take cuttings-Put it in rooting powder contain hormones encourages the plants to develop roots
Producing a genetically identical clone of plant through tissue culture
94
Explain how tissue culture clones plants
We take a plant and divided it into hundreds of tiny pieces and put it on an agar plate
Each piece contains a small number of cells
They are incubated with plant hormones
The plant hormone stimulates the part to grow and develop into a fully grown clones
Conditions must be sterile
Don’t want to introduce any microorganisms like fungi or bacteria
95
Tissue culture allows us to produce what..?
Thousands of genetically identical plants quickly and cheaply
96
How else can tissue culture be used for?
To preserve rare species of plants 
97
How do we clone animals?
Start with sperm and egg cell from horses with characteristics we want
Fertilisation occurs Producing a fertilised egg
We allowed the egg to develop into early-stage embryos
It’s important that the cells in the zebras have not started to specialise- any specific kind of cell
Now get a glass rod and split the embryo in two
We transfer the two embryos into host mother 
These embryos will grow and develop into the host mothers and produce two identical offsprings
98
What are the issues with Cloning animals using sexual reproduction?
We cannot be certain that will have characteristics we want as I’ll be a variation in the offspring 
99
What is the key benefits of adult cell cloning 
We are cloning from the adults- Will have the characteristics that we want because it’s fully developed- cells have already been specialised
100
Explain adult cell cloning?
Get skin cell from a animal
Take out nucleus from cell- Contains genetic information from the animal we are cloning
Get egg from female sheep. Remove nucleus from unfertilised egg cell
now has no genetic material
put the nucleus from the skin cell into the egg
now contains only genetic information from the animal we are cloning
we give the egg an electric shock because in the cell to divide forming an embryo
the genetic information is the same to the adults can sell we started with
once it has formed into a ball of cells it’s inserted into the womb of the host mother to develop
101
Why does the clone look nothing like the host mother?
Clone does not contain any of the genetic material
102
What did Lamarck think?
If a characteristic was regularly Use it became more developed
This strengthened the characteristic and was passed on to the offspring
103
What was Wallace interested in?
Warning ⚠️ colours in animals
104
What is speciation?
New species being formed
105
describe how Wallace said speciation occurs 
Geographical barriers separating two species
Before there was a population with all of the same species that could interbreed 
Meaning any useful mutation can spread throughout the whole population
The river may change course and separate the two populations making the snails into two groups
Because they’re now separate there’s no interbreeding between the two groups
Natural selection will favour different alleles on the two sides of the island - food sources may be different
Because they’re two different groups now interbreed different mutations cannot spread between the two populations
This will lead to over generations to 2 populations of snails to change
If the river then change the course again allows it to mix the phenotypes
are so different that they cannot interbreed or reproduce To make fertile offspring
now the snails are two different species
106
What do genes Determine?
The sequence of amino acids
107
Is that are you for cystic fibrosis recessive or dominant
Recessive c
108
is the allele for polydactyly dominant or recessive
Dominant P
109
What did Mendel determine after testing inheritance on pea plants?
That characteristics are not blended into the offspring
Some characteristics can be masked and then reappear in later generations-Recessive alleles
He found out that actually
Genes determine the offspring and do not change when passed on to descendants
110
What are the two ways that Mendal was proven right?
Scientists discovered genes on chromosomes while discovering cell division
The structure of DNA in the mid-1900s
111
What are the two kingdoms that Linnaeus split Living organisms into?
Plant and animal kingdom
112
What is the binomial name?
Genus and species
113
What is classification based on
Physical features like the number of toes shape of body
114
How has the classification system changed?
We can now use microorganisms under microscope to view their biochemistry like DNA instead physical features
