Biology Paper 2 Flashcards
1
Q
Homeostasis
A
Regulation of internal conditions to maintain optimal conditions for enzymes and cellular function.
2
Q
Blood glucose levels
A
One of the internal conditions maintained by homeostasis.
3
Q
Body temperature
A
One of the internal conditions maintained by homeostasis.
4
Q
Water levels
A
One of the internal conditions maintained by homeostasis.
5
Q
Receptors
A
Detect stimuli (e.g. temperature, glucose levels).
6
Q
Coordination centres
A
Brain, spinal cord, pancreas.
7
Q
Effectors
A
Muscles or glands that bring about a response.
8
Q
CNS
A
Brain + spinal cord.
9
Q
Neurones
A
Carry electrical impulses from receptors to CNS to effectors.
10
Q
Reflex arc
A
Stimulus → receptor → sensory neurone → relay neurone → motor neurone → effector → response.
11
Q
Reflexes
A
Automatic and rapid responses that don’t involve the conscious brain.
12
Q
Cerebral cortex
A
Responsible for consciousness, intelligence, and memory.
13
Q
Cerebellum
A
Responsible for muscle coordination.
14
Q
Medulla
A
Controls unconscious activities (e.g. breathing).
15
Q
Retina
A
Light receptors in the eye.
16
Q
Optic nerve
A
Carries impulses to the brain.
17
Q
Sclera
A
Tough outer layer of the eye.
18
Q
Cornea
A
Refracts light.
19
Q
Iris
A
Controls pupil size.
20
Q
Ciliary muscles + Suspensory ligaments
A
Control lens shape.
21
Q
Accommodation
A
Adjustment of lens shape for near or far objects.
22
Q
Myopia
A
Short-sightedness; focus before retina.
23
Q
Hyperopia
A
Long-sightedness; focus behind retina.
24
Q
Control of Body Temperature
A
Controlled by thermoregulatory centre in the brain; involves skin receptors.
25
Vasodilation
Response to being too hot; sweating occurs to lose heat.
26
Vasoconstriction
Response to being too cold; conserves/makes heat.
27
Negative feedback mechanisms
Processes that maintain homeostasis by counteracting changes.
28
Endocrine System
Glands release hormones into blood → target organs.
29
Pituitary gland
Master gland that releases multiple hormones.
30
Control of Blood Glucose
High glucose → insulin → glucose moves into cells & stored as glycogen.
31
Type 1 diabetes
Pancreas doesn't produce insulin → treated with insulin injections.
32
Type 2 diabetes
Cells stop responding → treated with diet + exercise.
33
Negative feedback
Low glucose → glucagon → glycogen converted back to glucose.
34
Water loss
Water lost via lungs (breathing) & skin (sweat) - not controlled.
35
Kidneys
Control loss of water via urine: Filtration + selective reabsorption.
36
ADH
Controls water reabsorption in kidneys; more ADH = more water reabsorbed.
37
Dialysis
A treatment for kidney failure that filters waste from the blood.
38
Kidney Transplant
Surgical procedure to replace a diseased kidney with a healthy one.
39
Oestrogen
Main female hormone produced by ovaries.
40
Testosterone
Main male hormone produced by testes.
41
Menstrual cycle
FSH: egg matures; LH: egg released (ovulation).
42
Contraception
Methods to prevent pregnancy, including hormonal and non-hormonal options.
43
Fertility drugs
FSH + LH to stimulate ovulation.
44
IVF
Collect eggs, fertilise in lab, implant embryos.
45
Adrenaline
Hormone that increases heart rate and oxygen/glucose to brain & muscles during stress/fear.
46
Thyroxine
Hormone that regulates metabolism, controlled by negative feedback.
47
Auxins
Plant hormones that control phototropism (light) + gravitropism (gravity).
48
Gibberellins
Plant hormones that trigger seed germination.
49
Ethene
Plant hormone that controls fruit ripening.
50
Sexual reproduction
Fusion of gametes (sperm + egg in animals, pollen + egg in plants) producing genetically different offspring.
51
Asexual reproduction
One parent, no fusion of gametes, producing genetically identical clones.
52
Meiosis
Cell division that results in four gametes, each with half the number of chromosomes.
53
DNA
Polymer made of two strands forming a double helix, found in chromosomes.
54
Gene
Section of DNA coding for a protein.
55
Genome
Entire genetic material of an organism.
56
Dominant allele
Always expressed in the phenotype.
57
Recessive allele
Only expressed if no dominant allele is present.
58
Polydactyly
Dominant genetic disorder characterized by extra fingers/toes.
59
Cystic fibrosis
Recessive genetic disorder affecting cell membranes.
60
Gamete
A sex cell (sperm or egg in animals; pollen or egg in plants) that carries half the number of chromosomes.
61
Pituitary gland
"Master gland" - releases multiple hormones.
62
Kidneys
Control loss via urine: Filtration + selective reabsorption.
63
Excess amino acids
Deaminated in liver → ammonia → urea.
64
ADH
(from pituitary) controls water reabsorption in kidneys.
65
Dialysis
Time-consuming, expensive in the long term, must follow strict diet/fluid limits.
66
Kidney Transplant
Can be a permanent solution, no need for regular dialysis, improves quality of life.
67
Oestrogen
Main female hormone.
68
Testosterone
Main male hormone.
69
FSH
Stimulates egg maturation.
70
LH
Triggers egg release (ovulation).
71
Menstrual cycle
Involves hormones like FSH and LH for egg maturation and release.
72
Contraception
Hormonal: pill (oestrogen/progesterone), patch, injection, implant; Non-hormonal: condoms, diaphragm, IUD, spermicides, surgery.
73
Adrenaline
Increases heart rate, oxygen/glucose to brain & muscles during stress/fear.
74
Thyroxine
Regulates metabolism → controlled by negative feedback.
75
Auxins
Control phototropism (light) + gravitropism (gravity).
76
Gibberellins
Trigger seed germination.
77
Ethene
Controls fruit ripening.
78
Asexual reproduction
One parent, no fusion of gametes producing genetically identical clones.
79
Meiosis
Cell divides twice → 4 gametes (each with half chromosomes).
80
DNA
Polymer made of two strands forming a double helix.
81
Polydactyly
Dominant genetic disorder resulting in extra fingers/toes.
82
Sex determination
XX = female, XY = male; 23rd pair of chromosomes controls sex.
83
Vasodilation
The widening of blood vessels to lose heat.
84
Sweating
The process of losing heat through moisture on the skin.
85
Vasoconstriction
The narrowing of blood vessels to conserve or generate heat.
86
Shivering
The involuntary contraction of muscles to generate heat.
87
Negative feedback mechanisms
Processes that counteract changes in the body to maintain homeostasis.
88
Endocrine System
A system where glands release hormones into the blood to target organs.
89
Pituitary gland
The 'master gland' that releases multiple hormones.
90
Insulin
A hormone that allows glucose to move into cells and be stored as glycogen.
91
Type 1 diabetes
A condition where the pancreas doesn't produce insulin, treated with insulin injections.
92
Type 2 diabetes
A condition where cells stop responding to insulin, treated with diet and exercise.
93
Glucagon
A hormone that converts glycogen back to glucose when blood glucose is low.
94
ADH
A hormone from the pituitary that controls water reabsorption in kidneys.
95
Dialysis
A treatment that filters waste from the blood when kidneys are not functioning.
96
Kidney Transplant
A surgical procedure to replace a diseased kidney with a healthy one.
97
Oestrogen
The main female hormone produced by the ovaries.
98
Testosterone
The main male hormone produced by the testes.
99
FSH
Follicle-stimulating hormone that helps egg maturation.
100
LH
Luteinizing hormone that triggers ovulation.
101
Fertility drugs
Medications that contain FSH and LH to stimulate ovulation.
102
IVF
In vitro fertilization, a process of fertilizing eggs in a lab and implanting embryos.
103
Adrenaline
A hormone released by adrenal glands that increases heart rate in response to stress.
104
Thyroxine
A hormone that regulates metabolism, controlled by negative feedback.
105
Auxins
Plant hormones that control phototropism and gravitropism.
106
Ethene
A plant hormone that controls fruit ripening.
107
Sexual reproduction
The fusion of gametes to produce genetically different offspring.
108
Asexual reproduction
Reproduction involving one parent that produces genetically identical clones.
109
Meiosis
A type of cell division that results in four gametes, each with half the chromosome number.
110
DNA
A polymer made of two strands forming a double helix, found in chromosomes.
111
Genome
The entire genetic material of an organism.
112
Polydactyly
A genetic disorder characterized by extra fingers or toes, inherited as a dominant trait.
113
Cystic fibrosis
A recessive genetic disorder affecting cell membranes.
114
Gamete
A sex cell that carries half the number of chromosomes.
115
Chromosome
A long DNA molecule containing many genes, found in the nucleus.
116
ADH
Controls water reabsorption in kidneys; more ADH = more water reabsorbed (when blood is too concentrated).
117
Adrenaline
Stress/fear → increases heart rate, oxygen/glucose to brain & muscles.
118
Sexual reproduction
Fusion of gametes (sperm + egg in animals, pollen + egg in plants) produces genetically different offspring.
119
Asexual reproduction
One parent, no fusion of gametes, produces genetically identical clones.
120
Polydactyly
Dominant (extra fingers/toes).
121
Cystic fibrosis
Recessive (disorder of cell membranes).
122
Humans
Humans have 23 pairs of chromosomes.
123
Gene
A short section of DNA on a chromosome that codes for a specific protein.
124
Allele
Different versions of the same gene (e.g. blue or brown eye colour).
125
Dominant
An allele that is always expressed in the phenotype, even if only one copy is present.
126
Recessive
An allele that is only expressed in the phenotype if two copies are present (no dominant allele).
127
Homozygous
Having two identical alleles for a gene (e.g. BB or bb).
128
Heterozygous
Having two different alleles for a gene (e.g. Bb).
129
Genotype
The combination of alleles an organism has (e.g. BB, Bb, or bb).
130
Phenotype
The physical characteristics or traits expressed by the genotype (e.g. brown eyes).
131
Variation
Due to genes (genetic), environment, or both combined.
132
Mutations
Mutations occur all the time.
133
Evolution
Change in inherited traits over generations
134
Natural Selection
Occurs by natural selection
135
Beneficial Traits
More likely to be passed on
136
Speciation
Occurs when populations can't interbreed
137
Selective Breeding
Humans breed animals/plants for desirable traits
138
Selective Breeding Steps
Select parents with desired trait, breed, select best offspring, repeat
139
Selective Breeding Examples
Disease resistance, high milk yield, gentle pets
140
Selective Breeding Risks
Inbreeding leads to increased risk of genetic disorders
141
Genetic Engineering
Transfer genes from one organism to another
142
Genetic Engineering Uses
GM crops (bigger yield, disease/pest resistance), bacteria producing insulin
143
Genetic Engineering Pros
Improve crops, medicine
144
Genetic Engineering Cons
Impact on wild plants/animals, ethical concerns
145
Plant Cloning
Tissue culture: few cells → full plant (rare species nurseries)
146
Animal Cloning
Embryo transplant: split early embryo → identical clones
147
Adult Cell Cloning
Nucleus from adult cell → inserted into empty egg, electric shock → divides into embryo → implanted in surrogate
148
Animal Cloning Pros
Preserve endangered species, desirable traits
149
Animal Cloning Cons
Ethical issues, reduced gene pool
150
Fossils
Show changes in organisms over time
151
Fossil Formation
Formed from hard parts not decayed, replacement by minerals, traces like footprints
152
Incomplete Fossil Record
Due to soft-bodied organisms and geological activity
153
Antibiotic-Resistant Bacteria
Bacteria reproduce quickly → mutations; some resistant strains survive and spread (e.g. MRSA)
154
Preventing Antibiotic Resistance
Avoiding overuse of antibiotics, finishing full course, limiting use in farming
155
Classification
Linnaeus System: Kingdom → Phylum → Class → Order → Family → Genus → Species
156
Binomial Name
Genus + Species (e.g. Homo sapiens)
157
Three-Domain System
Archaea - primitive bacteria, Bacteria - true bacteria, Eukaryota - animals, plants, fungi, protists
158
Evolutionary Trees
Show common ancestors and evolutionary relationships
159
Ecosystem
Interaction of a community of living organisms (biotic) with non-living (abiotic) parts of the environment
160
Levels of Organization
Individual → Population → Community → Ecosystem
161
Interdependence
Species rely on others (e.g. food, shelter, pollination)
162
Stable Community
All species and environmental factors in balance
163
Biotic Factors
Living things affecting survival: availability of food, new predators, new pathogens, competition between species
164
Abiotic Factors
Non-living things affecting survival: light intensity, temperature, moisture levels, soil pH + mineral content, wind intensity/direction, CO₂ levels (plants), O₂ levels (aquatic animals)
