Biology: Inheritance, Variation and Evolution Flashcards
1
Q
what are chromosomes
A
long molecules of DNA
2
Q
what is DNA
A
chemical that all of the genetic material in a cell is made up of
3
Q
what do chromosomes always come in
A
pairs
4
Q
how many chromosomes do humans have
A
46
5
Q
what is a gene
A
small section of DNA found on a chromosomes
6
Q
what do genes do
A
contain instructions for cells to make a specific protein
7
Q
what is a genome
A
entire set of genetic material in an organism
8
Q
what is DNA made up of
A
the monomer nucletide
9
Q
what does a nucleotide contain
A
one sugar molecule, one phosphate molecule and one base
10
Q
what does the sugar and phosphate molecule do in the nucleotide
A
forms the backbone of the DNA strands
11
Q
what are the bases within a nucleotide
A
A, T, C, G
12
Q
what do the bases do
A
pair up with a base on the opposite side of the double helix called complementary pairing
13
Q
which bases pair with which
A
A always pairs with T
C always pairs with G
14
Q
what does the order of the bases decide
A
order of amino acids in a protein
15
Q
other than coding protein what does DNA do
A
non coding parts switch genes on and off
16
Q
what is mRNA
A
molecule that acts as a messenger between DNA and ribosomes carrying code for how to make protein
17
Q
give 3 general uses of proteins in the body
A
Enzymes
Hormones
Structural Protein
18
Q
what are mutations
A
random changes in an organisms DNA
19
Q
what do mutations do
A
change the sequence of the DNA bases
20
Q
what are the three examples of mutations
A
Insertions
Deletions
Substitutions
21
Q
what are Insertion mutations
A
a new base is inserted into the DNA base sequence where it shouldn’t be
22
Q
what are deletion mutations
A
when a random base is deleted from the DNA sequence
23
Q
what are substitution mutations
A
random base in the DNA sequence is changed to a different base
24
Q
what are the two types of reproduction
A
sexual
asexual
25
what is sexual reproduction
involves the fusion of male and female gametes. Because there are two parents the offspring contains a mixture of their parent's genes
26
what is asexual reproduction
one parent that replicates their own DNA to clone themselves. The offspring is genetically identical to the parent
27
how does sexual reproduction happen
meiosis
28
how does asexual reproduction happen
mitosis
29
which organisms reproduce asexually
bacteria, plants some animals
30
which organisms reproduce sexually
most animals and some flowering plants
31
what are gametes
sex cells that contain only one copy of chromosomes
| X and Y
32
what is the first step of meiosis
before the cell divides it duplicates its genetic information. After this duplication the chromosomes arrange themselves in pairs
33
what is the second stage of meiosis
the first division in meiosis happens as the chromosome pairs line up in the centre of the cell
34
what is the third stage of meiosis
the pairs are pulled apart so each new cell has only one copy of each chromosome.
35
what is the fourth stage of meiosis
the chromosomes line u agiain in the centre of the cell and the arms of the chromosomes are pulled apart for the second division
36
what is the end product of meiosis
four gamete cells with only a single set of chromosomes in it
37
what happens to the cell that is produced when gamete cells fuse together
the resulting cell divides by mitosis to make a copy of itself multiple times to create an embryo
38
what are the four advantages of sexual reproduction
there is variation between parents and offspring
Variation increases a species chances of surviving
Properly adapted individuals are more likely to breed
Selective breeding can be used to get a certain trait which speeds up natural selection
39
what are the four advantages of asexual reprroduction
only need one parent
uses less energy
faster
many offspring can be produced
40
how many pairs of chromosomes are matched pairs
22
41
what is the 23rd pair of chromosomes for
It decides your sex
42
what sex is the XY chromosome
Male
43
what sex is the XX chromosome
Female
44
what is an allele
different versions of genes
45
what is homozygus
when you have two of the same allele
46
what is hetrozygus
when you have two different versions of a gene
47
what two types of allele are there
dominant and recessive
48
what is genotype
combination of alleles you have
49
what is phenotype
characteristics you have
50
what allele causes cystic fibrosis (mucus blocks airways)
recessive allele
51
what allele causes polydactyly (extra fingers or toes)
dominant allele
52
what are the three reasons against embryonic screening
prejudice against people with disorders
parents might want to chose a more desirable child
expensive
53
what are the three reasons for embryonic screening
stop people suffering
saves money for treating disorders
laws to stop parents being to prejudice
54
what did Gregor Mendel do
genetic experiments with peas
55
what three important conclusions did Mendel reach
Characteristics in plants are determined by hereditary units
Hereditary units are passed onto offspring unchanged from both parents
Hereditary units can be recessive or dominant
56
what are the two types of variation
genetic variation
| environmental variation
57
what causes genetic variation
different genes
58
what causes environmental variation
conditions in the environment for example sunlight
59
what else can cause variation
Mutations
60
what is the theory of evolution
All of today's species have evolved from simple life forms that first started to develop over three billion years ago
61
what is speciation
development of a new species
62
what is extinction
no individuals of a species remain
63
what 5 things can cause extinction
```
Environment changes too quickly
New predator kills them all
New disease kills them all
Can't compete with another species for food
Catastrophic event kills them all
```
64
what is natural selection
where the species that is most adapted and suited to its environment survives and reproduces passing on its characteristics developing them further
65
what is selected breeding
take the organisms that have the desired traits or characteristics and you breed them together to produce an offspring with the desired characteristics
66
why is selective breeding bad
reduces the gene pool so that the species is less likely to be able to adapt to a change
67
what is genetic engineering
transfer genes responsible for a desired characteristic from one organism to another so that it gains the desired characteristic
68
what is the first step of genetic engineering
Useful gene is isolated and cut from one organism's genome using enzymes and inserted into a vector
69
what is the second step of genetic engineering
The vector is usually a virus or bacterial plasmid and is introduced to the target organism and the gene is inserted
70
why is genetic engineering controversal
The new genes may have unforeseen side effects which pass onto future generation
71
give 3 cons of GM crops
Reduce farmland biodiversity
Unsafe as we dont fully understand the effects on health
The transplanted genes get out into environment making pests immune to pesticides
72
give 3 pro of GM crops
Characteristics can increase the yield
Engineered to contain more nutrients we lack
Currently we have encountered no problems
73
What is cloning
Where you recreate an organism that is genetically identical to its parent
74
What are the two methods for cloning plants
Tissue Culture
| Cuttings
75
How does tissue culture work
Few plants cells put in a growth medium with hormones and they grow into new plants which are clones of their parents
76
what are the benefits of Tissue Culture
Plants made very quickly
Very little space required
Grown all year
77
How does cuttings work
take cuttings from good parent plants and then plant them to reproduce clones of parent
78
what are the benefits of cuttings
Produced quickly
Produced cheaply
Simpler than tissue culture
79
what two ways can you clone an animal
Embryo transplant
| Adult cell cloning
80
how does embryo transplant work
take sperm and egg cells form two best animals
artificially fertilise egg to produce embryo then split it to produce multiple clones
Cloned embryos implanted into surrogates
81
how does adult cell cloning work
take unfertilised egg cell and remove nucleus
insert nucleus taken form adult skin cell
stimulate egg with electric shock to produce embryo
implant embryo into surrogate
82
what are the 3 issues surrounding cloning
reduces gene pool
cloning could produce unhealthy offspring
humans could be cloned in future with severe problems
83
what are fossils
remains of plants and animals
84
what are the three ways fossils form in rocks
gradual replacement by minerals
casts and impression
preservation where no decay happens
85
how does gradual replacement by minerals happen
things like bones dont decay easily and last long time when buried. They are eventually replaced by minerals as they decay forming rock like substance. Surrounding sediments also turn to rock
86
how does casts and impressions happen
organism is buried in soft material. This material later hardens around organism as it decays leaving a cas or impression of itself
87
how does preservation happen
in amber and tar pits there is no oxygen or moisture so decay microbes cant survive. In glaciers its too cold and peat bogs are too acidic
88
what is a species
group of similar organisms that can reproduce to give fertile offspring
89
when does speciation occur
populations of the same species become so different that they can no longer successfully interbreed to produce fertile offspring
90
what two things lead to speciation
Isolation and Natural selection
91
how do bacteria become resistant to antibiotics
overtime they adapt and evolve to become resistant to antibiiotics
92
what is an example of a superbug
MRSA
93
what are the two reasons for antibiotic resistant bacteria emerging
Overuse of antibiotics
| Inappropriate use of antibiotics
94
what is classification
organising living organisms into groups
95
what is the order of classifications from largest to smallest
domain --> kingdom --> phylum --> class --> family--> Genus --> species
96
what are the three domains
Archaea
Bacteria
Eukaryota
97
what are archaea
primitive bacteria normally found in extreme places
98
what is the Binomial system
System that determines how organisms are named
99
what does the first part of the binomial name refer to
genus the organism belongs to
100
what does the second part of the binomial name refer to
species of the organisms
