GCSE BIOLOGY FLASHCARDS
1
Q
Pupil
A
Centre of the iris, it varies in size to regulate the amount of light that reaches the retina
2
Q
Iris
A
Made up of muscles called circular and radial muscles that work antagonistically to regulate the size of the pupil
3
Q
Reflex response to dim light
A
Circular muscles relax, radial muscles contract, pupil dilates so that more light can enter the eye
4
Q
Reflex response to bright light
A
Circular muscles contract, radial muscles relax, pupil constricts so that less light can enter the eye
5
Q
Cornea
A
Focuses the entry of light into the eye but is fixed and unable to adjust its focus
6
Q
Lens
A
Focuses light rays to the back of the eye and can change shape to adjust focus for distant and near objects
7
Q
Retina
A
The light-sensitive surface at the back of the eye containing receptor cells that detect light
8
Q
Accommodation
A
The process by which the eye lens changes shape to focus on near or distant objects
9
Q
Focusing on a near object
A
Ciliary muscles contract, suspensory ligaments loosen, lens is thicker and refracts light rays strongly
10
Q
Focusing on a distant object
A
Ciliary muscles relax, suspensory ligaments pull tight, lens is pulled thin and only slightly refracts light rays
11
Q
Convex lenses
A
Used for correcting hyperopia by moving an image forward and focusing it on the retina
12
Q
Concave lenses
A
Used for correcting myopia by moving an image further back and focusing it on the retina
13
Q
Nervous system
A
The network of nerve cells and fibres that transmits nerve impulses between parts of the body
14
Q
Neurones
A
Basic cells of the nervous system that carry electrical impulses around the body
15
Q
Electrical impulses
A
Electrical impulses
The impulses or signals that are carried by neurones
16
Q
Central nervous system (CNS)
A
The brain and the spinal cord
17
Q
Stimulus
A
A change in an organism’s surroundings
18
Q
Receptors
A
Special structures that allow living organisms to sense the conditions of their internal or external environment
19
Q
Sense organs
A
Clusters of receptor cells that respond to specific stimuli such as light, sound, touch, temperature, chemicals and then relay this information as electrical impulses along neurones to the central nervous system
20
Q
Coordinator
A
The central nervous system which formulates a response to a stimulus before sending impulses to an effector
21
Q
Response
A
A reaction to a stimulus
22
Q
Reflex arc
A
A shorter nerve pathway involved in a reflex action made up of a sensory neurone, relay neurone and a motor neurone
23
Q
Neurotransmitter
A
A chemical that is released from the ends of an active neurone and diffuses across the synapse to other neurones
24
Q
Dendron
A
A branch at the end of a neurone that meets up with other neurons to pass on nervous impulses, via the synapse
25
Axon
The main thread-like extension of a neurone that carries nerve impulses
26
Brain
A mass of nerve tissue consisting of billions of interconnected neurones that acts as the main control centre of the nervous system
27
Brain mapping
A set of neuroscience techniques used to create a map of the various brain areas and their functions
28
Neuroscientist
A scientist who studies the brain and nervous system
29
Magnetic resonance imaging (MRI)
Can be used to look at which parts of the brain are most active during certain activities
30
MRI scanner
A type of scanner that uses strong magnetic fields and radio waves to produce images of inside of the body
31
Electrical stimulation
Can be used to look at behaviour in response to stimulation and narrow down specific brain regions to their functions
32
Cerebral cortex
The outer region of the cerebrum that contains sheets of nerve cells controlling memory, consciousness, language and intelligence
33
Cerebral hemispheres
The main part of the brain that is divided into a right hemisphere and a left hemisphere
34
Cerebellum
A large structure of the hindbrain that controls fine motor skills including balance and movement
35
Hindbrain
The lower part of the brainstem that include the cerebellum
36
Medulla oblongata
The base of the brainstem which controls heartbeat and breathing
37
Eye
A sense organ that detects light and is responsible for vision
38
Sclera
The white outer part of the eye that provides protection
39
Cornea
The transparent tissue that covers the front of the eye, it controls and focuses the entry of light into the eye
40
Iris
The coloured part of the eye behind the cornea that regulates the size of the pupil
41
Pupil
The dark opening in the centre of the pupil, it varies in size to regulate the amount of light that reaches the retina
42
Lens
A transparent structure located behind the iris that focuses light on the retina at the back of the eye
43
Ciliary muscles
Muscles which work with the suspensory ligaments to adjust the shape of the lens in order to focus on near or far objects
44
Suspensory ligaments
Ligaments which work with ciliary muscles to adjust the shape of the lens in order to focus on near or far objects
45
Retina
The light-sensitive surface at the back of the eye containing light and colour receptor cells
46
Optic nerve
The nerve that carries neural impulses from the receptor cells of the eye to the brain
47
Light receptor cells
Also called rod cells, these are highly light sensitive and are responsible for vision in dimly-lit conditions
48
Colour receptor cells
Also called cone cells, these can detect a wide spectrum of light and are responsible for the perception of colour
49
Stem cell
An undifferentiated cell which can become any type of cell
50
Undifferentiated
A cell which is not yet specialised
51
Differentiated
A cell which is specialised to a specific function
52
Human embryo
A source of stem cells which can become any type of cell
53
Bone marrow
A source of stem cells which can become many types of cell including blood cells
54
Meristem
The region in plant shoots and roots where mitosis occurs and a source of stem cells in plant tissue
55
Diabetes
A disease of the pancreas which may be treated with stem cells
56
Spinal cord injury
A cause of paralysis which may be treated with stem cells
57
Therapeutic cloning
When an embryo is produced with the same genes as the patient as a source of stem cells
58
Potential risks of stem cell treatment
Viral infection, cancer and rejection unless therapeutic cloning is used
59
Zygote
A fertilised egg cell which divides to form an embryo
60
Ethical objections
Moral reasons people may be against stem cell treatments
61
Religious objections
Religious reasons people may be against stem cell treatments
62
Advantages of bone marrow stem cells
Can treat many blood-linked or immune-linked diseases, less ethical concerns than embryonic stem cells, bone marrow is easier to obtain than embryonic cells
63
Advantages of embryonic stem cells
No consent required, obtainable via embryos discarded in IVF, can be used to make any type of cell, less risk of rejection if used via therapeutic cloning
64
Disadvantages of bone marrow stem cells
Requires voluntary donors, bone marrow extraction can cause pain to an individual and requires consent, may have a risk of infection, can only form cells such as blood cells, risk of rejection
65
Disadvantages of embryonic stem cells
Disadvantages of embryonic stem cells
Ethical considerations such as potential loss of life or harm to embryo, less easily obtainable than bone marrow stem cells, risk of rejection
66
Sperm cell
An animal cell with a head containing genetic material for fertilisation and a tail for swimming to the egg cell
67
Nerve cell
An extended animal cell with many branches that sends electrical messages around the body
68
Muscle cell
An animal cell that contains sliding protein fibres to contract and allow movement
69
Red blood cell
An animal cell that has lost its nucleus to make remove for haemoglobin, a protein that binds to oxygen
70
Intestinal epithelial cell
An animal cell that is responsible for molecule absorption in the intestines, these cells have many tiny folds called microvilli that increase the surface area for absorption
71
Root hair cell
A plant cell which has a large surface area and thin walls to absorb water and minerals
72
Xylem cell
A hollow plant cell with thick walls containing lignin to transport water and minerals through the plant
73
Phloem cell
A living plant cell with sieve plate pores to transport dissolved sugars throughout the plant
74
Cell differentiation
A process where cells change shape and structure to produce different functions
75
Undifferentiated cell
A cell that has not yet acquired a special structure or function, such as a stem cell
76
Cell division of undifferentiated cells
Occurs in developing organisms or embryos prior to cell specialization
77
Specialised cell
A cell which has differentiated to produce a new function
78
Myelin sheath
The fatty insulation of a nerve axon
79
Acrosome
Part of the head of a sperm cell that contains digestive enzymes to penetrate the egg cell
80
Cell
The basic building block of all living organisms, examples include skin cells and nerve cells
81
Tissue
A group of cells with a similar structure and function, such as muscular tissue or skeletal tissue
82
Organ system
A system of organs which work together to form organisms, such as the circulatory system or digestive system
83
Organism
A living thing such as a plant, animal or single-celled life form
84
Multicellular
Organisms that are made of multiple cells
85
Plant growth
Involves cell division and elongation, followed by differentiation
86
Percentile charts
Charts used to compare the growth of individual children with the expected average growth
87
Interpreting percentile charts
Each percentile shows a relationship between age and a factor such as weight or height, if an individual is at the 75th percentile that means that in a sample of 100 they are bigger than 75 individuals of the same age or smaller than 25 individuals of the same age
88
Cancer
Any malignant growth or tumour caused by abnormal and uncontrolled cell division
89
Uncontrolled growth
When cells lose the ability to control growth
90
Cell division
Process by which a cell divides into new daughter cells
91
Benign tumour
A lump of cells that cannot invade neighbouring tissues or spread throughout the body
92
Abnormal cell
When cell growth and division not under normal control processes
93
Malignant tumour
Lump of cells that have developed the ability to travel to other parts of the body
94
Secondary tumour
A lump of cells formed from a cell transported from a primary tumour
95
Carcinogen
A cancer-causing substance
96
Ionising radiation
Type of radiation such as UV, X-ray or gamma rays that can cause mutations in DNA
97
Smoking
A risk factor for lung cancer
98
Genetic risk factor
Specific genes which increase the risk of certain health problems
99
Lifestyle risk factor
Specific actions which increase the risk of certain health problems
100
Mutation
A change in a gene or chromosome
101
Radiotherapy
A treatment for cancer using radiation
102
Chemotherapy
A treatment for cancer using drugs
103
Chromosomes
Molecules of tightly-packed DNA that contain many genes
104
DNA molecules
Chemical molecules found in every living organism that hold instructions for growth and development
105
Genetic material
The general term for the material used to store genetic information in a cell
106
Genes
A small section of DNA that controls a specific characteristic
107
Nucleus
Contains the genetic material in a eukaryotic cell
108
Nuclear envelope
A double membrane perforated with pores that control the flow of materials in and out of the nucleus
109
Cell cycle
Repeating phases of cell growth, replication and division in cells
110
Growth phase
When the cell grows and increases its number of sub-cellular structures such as mitochondria and ribosomes
111
Replication phase
When the cell doubles its genetic material by synthesising new DNA
112
Cell division
When one cell divides to form two or more daughter cells
113
Mitosis
A type of cell division where two identical daughter cells are formed with the same genetic material as the parent cell
114
Daughter cells
The new cells formed as a result of the division of a cell
115
Reasons for mitosis
Growth, repair and development of multicellular organisms
116
Asexual reproduction
How some organisms reproduce to form identical offspring using mitosis
117
Chromosome pairs
How chromosomes are normally found in body cells
118
Body cell
A typical cell that undergoes mitosis and is not involved in sexual reproduction
119
Interphase
The cell grows, replicates its DNA, performs its normal functions and prepares for division by mitosis
120
Prophase
The start of mitosis where chromosomes become visible under a microscope, the nuclear envelope dissolves and spindle fibres form
121
Metaphase
The second phase of mitosis, during which the chromosomes line up across the centre of the cell
122
Anaphase
The third phase of mitosis, during which the chromosome pairs separate and move toward opposite poles along spindle fibres
123
Telophase
The final phase of mitosis, in which the chromosomes arrive at opposite ends of the cell, the spindle fibres disassemble and the formation of two new nuclei occurs
124
Cytokinesis
The division of the cytoplasm and cell membranes to form two separate daughter cells, following mitosis
