Biology unit 2 Flashcards
(90 cards)
1
Q
what is deoxyribonucleic acid
A
DNA molecules
2
Q
what are chromosomes
A
strands of DNA, usually arranged in pairs in the nucleus of each cell
3
Q
what does cytosine pair with
A
guanine
4
Q
what is an allele
A
the form of a gene
5
Q
what does double helix mean
A
2 strands of genes in a spiral shape
6
Q
what does the triplet code determine
A
which amino acid is next linked (by a chemical bond) in the protein chain
7
Q
DNA has a ladder-like structure, it is made of 2 long chains of alternating _____ and ________ molecules
A
sugar and phosphate
8
Q
what are the 4 different bases that make up DNA
A
Adenine
Thymine
Cytosine
Guanine
9
Q
what does adenine pair with
A
thymine
10
Q
what does thymine pair with
A
adenine
11
Q
what does guanine pair with
A
cytosine
12
Q
where does protein synthesis take place
A
in the cytoplasm
13
Q
who discovered genetic profiling
A
Alec Jeffries in 1984
14
Q
what are gametes
A
sex cells
15
Q
what are the gametes of humans called
A
sperm and egg
16
Q
what is a diploid
A
a full chromosome set (body cell)
17
Q
what is a haploid
A
gametes containing half chromosome number
18
Q
give 2 examples where DNA analysis is used
A
paternity testing, identifying suspects in crime cases
19
Q
what is a genotype
A
set of alleles an individual has that determines a characteristic
20
Q
who discovered inheritance
A
Gregor Mendel in the 1800’s
21
Q
what is a gamete
A
sex cells
22
Q
what are the human gametes
A
sperm and egg
23
Q
why do gametes only contain half of the genetic information needed to form a new individual
A
so, when fertilisation takes place, they contain the correct number of chromosomes
24
Q
what is a gene
A
a section of dna that codes to make a particular protein
25
what is an allele
different form/version of the gene
26
what is a phenotype
the appearance of an organism as a result of its genotype/genes
27
what is heterozygous
an individual that has two different alleles for a characteristic
28
what is dna
the chemical that forms genes
29
what is homozygous
an individual that has two of the same alleles for a characteristic
30
what is a dominant gene
only 1 of these alleles is needed for the characteristic to be shown
31
what is a recessive gene
two of these alleles are needed for the characteristic to be shown
32
what is a chromosome
a structure containing genes
33
describe some ways in which humans may vary
eye colour, hair colour, height
34
what are the two main causes of variation
genetic and environmental
35
what lifestyle choices/factors might be responsible for causing environmental variation between individuals
diet, climate, habitat, diseases, culture
36
what is continuous variation
every individual has the characteristic, but it differs for each individual
37
what is discontinuous variation
every individual either has the characteristic or they do not
38
example of continuous variation
height, weight
39
example of discontinuous variation
tongue rolling, attached ear lobes
40
how is continuous variation shown on a graph
bar graph with bars touching and a bell-shaped curve
41
how is discontinuous variation shown on a graph
bar graph with bars separated, shown as discrete groups
42
define the word clone
genetically identical
43
what is ionising radiation
high frequency radiation that damages dna
44
what are liposomes
tiny bubbles within a spray used in gene therapy. they act as a vector to transmit the normal genes into the body
45
name 2 advantages of gm plants
- pest/disesease resistant crops so higher yields
- medicine can be made by gm organisms e.g insulin
46
name 2 disadvantages of gm plants
- superweeds may be created if pollen from gm crops is spread to non gm plants
- unknown effects of eating new protein produced in gm crops
47
what is mitosis
cell division where each division produces 2 daughter cells which have the same number of chromosomes (diploid) and are genetically identical to the mother cell.
48
what does mitosis do
allows organisms to grow, replace worn out cells and repair damaged tissues
49
what does meiosis do
produces gametes (sex cells)
50
what is meiosis
produces 4 daughter cells in every division which have half the number of chromosomes (haploid) and are genetically different to the mother cell
51
what are stem cells
undifferentiated cells which have the ability to develop into different types of specialised cell
52
where are stem cells found in plants
in the tip of the roots and shoot
53
where are stem cells found in animals
bone marrow (adult stem cell)
embryos (embryonic stem cells)
54
name 2 problems of using embryonic stem cells
there are ethical issues as to if it is a destruction of life
potential rejection from the body as it is not their own cells
55
name 2-4 advantages of adult stem cells
no rejection (if own cells)
no need to find a donor
no destruction of life (not as controversial)
no need for tissue typing
56
give 3 examples of specialised cells
muscle cells
nerve cells
blood cells
57
name 3 sources of tissue stem cells
adult or foetal tissue e.g bone marrow
umbilical cord blood
aborted foetuses
58
name 2 current stem cell therapies
bone marrow transplants
skin grafting
59
what is interspecific competition
competition with other species
60
what is intraspecific competition
competition between same species
61
what are the physical properties of a gene
sequence of bases in the dna
62
what are the functional properties of a gene
the protein it makes
the role that the protein has
63
if the sense organ is the eye then what is the stimulus
light
64
if the sense organ is the ear then what is the stimuli
sound/gravity
65
if the sense organ is the nose then what is the stimulus
chemicals
66
if the sense organ is the tongue then what is the stimulus
chemicals
67
if the sense organ is the skin then what are the stimuli
pressure, temperature, texture
68
if the sense organ is the eye then what is the sense
sight
69
if the sense organ is the ear then what is the sense
hearing/balance
70
if the sense organ is the nose then what is the sense
smell
71
if the sense organ is the tongue then what is the sense
taste
72
if the sense organ is the skin then what is the sense
touch
73
sense organs are groups of ............... cells
receptor
74
sense organs respond to stimuli and relay information as ................ signals called .......... .............. to the brain
electrical
nerve impluses
75
the central nervous system consists of the ........... and the ............. ...........
brain
spinal cord
76
what is the receptor
the change that is detected e.g a ball moving towards you
77
what is the receptor
the cells that detect the change e.g light sensitive cells in the retina
78
what neurones transmit information from the receptor to the co-Ordinator
sensory neurones
79
what neurones transmit information from the co-Ordinator to the effector
motor neurones
80
what is the co-Ordinator
this organises the information (brain/spinal cord)
81
what is the effector
causes the body to do something (muscle or gland) e.g muscles contract
82
what is the response
what the body does e.g catch the ball
83
what is a reflex
a fast, automatic reponse to stimulus that protects the body from harm
84
name 2 features of a reflex action
very fast
automatic
85
why do we have reflexes
to protect the body from harm
86
name a type of reflex
withdrawal reflexes e.g touching a hot or sharp object, for protection
87
what is a reflex arc
the pathway that messages follow in a reflex
88
what are the 3 neurones involved in the reflex arc
sensory
relay
motor
89
what is the synapse
a small gap between each neurone which release special chemicals called neurotransmitters to carry messages across the gap
90
what process helps neurotransmitters carry messages across gaps in-between neurones
diffusion
