Depth study (Knowledge) Flashcards
(165 cards)
1
Q
What does DNA code for, and why is it important?
Assess the effect of the cell replication processes on the continuity of the species
A
DNA codes for proteins, including hormones and enzymes, which control cellular functions and communication.
Why does DNA need to replicate exactly?
2
Q
What is meant by “continuity of species”?
Assess the effect of the cell replication processes on the continuity of the species
A
The ongoing survival of a species through the passing of characteristics from parents to offspring in a continuous lineage.
3
Q
Why is DNA replication essential for reproduction?
Assess the effect of the cell replication processes on the continuity of the species
A
It ensures enough genetic material is available to create new cells during reproduction.
4
Q
How does DNA replication support the continuity of species?
Assess the effect of the cell replication processes on the continuity of the species
A
It passes on fundamental life information, ensuring offspring inherit successful traits.
5
Q
What is the role of accurate DNA replication in evolution?
Assess the effect of the cell replication processes on the continuity of the species
A
It ensures offspring inherit favourable traits that contribute to evolutionary success.
6
Q
How does mitosis contribute to the continuity of species?
Assess the effect of the cell replication processes on the continuity of the species
A
It enables growth, tissue repair, and asexual reproduction, allowing organisms to reach maturity and reproduce.
7
Q
What is the role of mitosis in multicellular organisms?
Assess the effect of the cell replication processes on the continuity of the species
A
Mitosis enables development, maintenance, and repair of tissues by replacing old cells.
8
Q
How does mitosis function in asexual reproduction?
Assess the effect of the cell replication processes on the continuity of the species
A
Mitosis creates genetically identical offspring in organisms that reproduce asexually.
9
Q
What does meiosis produce and why is it important?
Assess the effect of the cell replication processes on the continuity of the species
A
Meiosis produces gametes, allowing genetic material from two parents to combine during fertilisation.
10
Q
How does meiosis introduce genetic variation?
Assess the effect of the cell replication processes on the continuity of the species
A
Through crossing over and independent assortment of alleles during gamete formation.
11
Q
Why is genetic variation from meiosis important for species continuity?
Assess the effect of the cell replication processes on the continuity of the species
A
It increases genetic diversity, which is crucial for survival, adaptation, and evolution.
12
Q
What is the balance between exact replication and variation?
Assess the effect of the cell replication processes on the continuity of the species
A
Most genetic material is copied exactly for proper function, while variation (via meiosis and mutation) allows adaptation.
13
Q
How do mutations affect continuity of species?
Assess the effect of the cell replication processes on the continuity of the species
A
Mutations introduce small genetic changes, potentially leading to beneficial traits and evolution.
A mutation is a permanent change in the DNA sequence of an organism. It can occur in a single nucleotide or involve large segments of DNA and may affect how genes function or are expressed.
14
Q
What are the three types of genotypes?
Model the formation of new combinations of genotypes produced during meiosis, including but not limited to:
- constructing and interpreting information and data from pedigrees and punnett squares
A
TT = homozygous dominant, tt = homozygous recessive, Tt = heterozygous.
15
Q
What is autosomal inheritance?
Model the formation of new combinations of genotypes produced during meiosis, including but not limited to:
constructing and interpreting information and data from pedigrees and punnett squares
A
The transmission of genes located on the autosomes (non-sex chromosomes).
16
Q
What are clues that a trait is autosomal?
Model the formation of new combinations of genotypes produced during meiosis, including but not limited to:
constructing and interpreting information and data from pedigrees and punnett squares
A
If sex-linked rules don’t apply (e.g., both sexes equally affected or male-to-male transmission exists).
17
Q
How do you identify a recessive trait in a pedigree?
Model the formation of new combinations of genotypes produced during meiosis, including but not limited to:
constructing and interpreting information and data from pedigrees and punnett squares
A
If an offspring has the condition but neither parent does, the trait is recessive.
18
Q
How do you identify a dominant trait in a pedigree?
Model the formation of new combinations of genotypes produced during meiosis, including but not limited to:
constructing and interpreting information and data from pedigrees and punnett squares
A
If an offspring does not have the trait but both parents do, the trait is dominant.
19
Q
What is sex linkage?
Model the formation of new combinations of genotypes produced during meiosis, including but not limited to:
constructing and interpreting information and data from pedigrees and punnett squares
A
It refers to genes located on sex chromosomes, usually the X chromosome, and often recessive.
20
Q
Why don’t sex-linked traits follow the Mendelian 3:1 ratio?
Model the formation of new combinations of genotypes produced during meiosis, including but not limited to:
constructing and interpreting information and data from pedigrees and punnett squares
A
Because males only have one X chromosome, so recessive alleles are more likely to be expressed.
21
Q
What are clues that a trait is sex-linked?
Model the formation of new combinations of genotypes produced during meiosis, including but not limited to:
constructing and interpreting information and data from pedigrees and punnett squares
A
Males are affected more, affected mothers pass the trait to sons, and there’s no male-to-male transmission.
22
Q
What is an example of a sex-linked condition?
Model the formation of new combinations of genotypes produced during meiosis, including but not limited to:
constructing and interpreting information and data from pedigrees and punnett squares
A
Haemophilia – a recessive disorder found on the X chromosome.
23
Q
What are multiple alleles?
Model the formation of new combinations of genotypes produced during meiosis, including but not limited to:
constructing and interpreting information and data from pedigrees and punnett squares
A
When more than two possible alleles exist for a gene, increasing potential genotypes.
24
Q
What is an example of multiple allele inheritance?
Model the formation of new combinations of genotypes produced during meiosis, including but not limited to:
constructing and interpreting information and data from pedigrees and punnett squares
A
The ABO blood group system (A, B, AB, and O blood types).
25
What tools help model genotype combinations during meiosis?
## Footnote
*Model the formation of new combinations of genotypes produced during meiosis, including but not limited to:
constructing and interpreting information and data from pedigrees and punnett squares*
Punnett squares and pedigrees.
26
Define **genetic variability**
The tendency at which traits in a population may vary
27
What can pedigrees help you determine?
## Footnote
*Model the formation of new combinations of genotypes produced during meiosis, including but not limited to:
constructing and interpreting information and data from pedigrees and punnett squares*
Inheritance type, genotypes of individuals, and likelihood of offspring inheriting a trait.
28
How do you calculate allele frequency?
## Footnote
*Collect, record and present data to represent frequencies of characteristics in a population, in order to identify trends, patterns, relationships and limitations in data, for example:
* examining frequency data*
Number of an allele in a population / total number of alleles in the population.
29
Define **gene pool**
All the alleles possessed by members in a population.
30
Define **genome**
The complete set of DNA in an organism
31
Define **genetic diversity**
total number of different alleles and the frequency of those alleles in a gene pool.
32
Define **population genetics**
Study of the genetic differences within a population, examining phenomena that have led to the observed differences.
33
What can frequencies that don't fulfill the HW equation show?
Microevolution
34
# *Hardy-Weinberg Equation*
What are the 5 assumptions of the equation?
## Footnote
*Collect, record and present data to represent frequencies of characteristics in a population, in order to identify trends, patterns, relationships and limitations in data, for example:
* examining frequency data*
1. no mutations
2. no gene flow
3. random mating
4. infinite population size
5. no selection pressures
35
What is the Hardy-Weinberg equilibrium?
## Footnote
*Collect, record and present data to represent frequencies of characteristics in a population, in order to identify trends, patterns, relationships and limitations in data, for example:
* examining frequency data*
a principle that states that allele and genotype frequencies in a population will remain constant from generation to generation, if certain conditions are met — meaning no evolution is occurring.
36
Define **polymorphism**
The occurrence of different forms among the members of a population also known as alternative phenotypes.
37
What is the Hardy-Weinberg equation and what does it represent?
## Footnote
*Collect, record and present data to represent frequencies of characteristics in a population, in order to identify trends, patterns, relationships and limitations in data, for example:
* examining frequency data*
p squared + 2pq + q squared = 1
* p squared = frequency of the homozygous dominant genotype
* 2pq = freqeuncy of the hetereozygous genotype.
* q squared = freqeuncy of the homozygous recessive genotype.
38
Define **allele freqeuncies**
## Footnote
Examinging frequency data
Represents the incidence of a gene variant in a population.
39
What is the Hardy-Weinberg equation used to calculate?
## Footnote
*Collect, record and present data to represent frequencies of characteristics in a population, in order to identify trends, patterns, relationships and limitations in data, for example:
* examining frequency data*
genotype frequencies in a population, based on given allele frequencies
40
What is an SNP?
## Footnote
analysing single nucleotide polymorphisms similarities
Single nucleotide polymorphism is a variation in a single nucleotide at a specific position on the genome.
41
What are SNPs called and why?
They are called genetic markers because they account for >90% of genetic differences and produce >1 allele
42
What is the effect of SNPs?
Depending on location and type, they can alter protein products, influencing physical, physiological, and behavioural traits.
43
How do scientists use SNPs?
To identify disease predispositions and locate nearby genes responsible for traits.
44
What are the limitations of SNPs?
Many SNPs are unassociated with traits and may have no functional effect on proteins.
45
What are the **3 types** of SNPs?
1. Unassociated SNP – No effect, occurs equally across traits.
2. Associated SNP – Linked to traits but doesn’t alter protein.
3. Causative SNP – Alters protein production or function.
46
Where are SNPs located?
In coding and non-coding regions of DNA
47
How are SNPs observed in a population?
They occur in >1% of the population and differ in frequency between groups
48
What effect do SNPs have on protein products?
* Noncoding SNPs: Affect amount of protein produced.
* Coding SNPs: Change amino acid sequence, potentially altering protein function.
49
# *GWAS (Genome-Wide Association Studies)*
What is GWAS and how does it use SNPs?
GWAS identifies genes associated with phenotypes by using SNPs as markers. If an SNP is close to a gene, it's likely inherited with it and thus associated with the trait.
50
How are GWAS conducted?
By comparing groups with different versions of a trait and analyzing SNP patterns to find associations between genes and traits.
51
What 3 things does a study of animals develop for humans?
* Methods of finding genes
* Understanding how genes work together
* Insights into gene evolution
52
How are associations evaluated in GWAS?
* Count how many times each allele appears in each trait group
* Calculate the difference for each allele between groups
* Add all differences across alleles
* A stronger total difference = stronger association
53
What is DNA technology?
## Footnote
*IQ5: Investigate the use of technologies to determine inheritance patterns in a populations
using, for example – DNA sequencing and profiling*
Specialised biological tools (mainly enzymes) used to modify, measure, manipulate, or manufacture DNA. Most tools come from organisms like bacteria.
54
# DNA revision
What is DNA?
## Footnote
*IQ5: Investigate the use of technologies to determine inheritance patterns in a populations
using, for example – DNA sequencing and profiling*
DNA is a biopolymer, made up of many repeating units (monomers) joined together
55
What are monomers in DNA?
## Footnote
*IQ5: Investigate the use of technologies to determine inheritance patterns in a populations
using, for example – DNA sequencing and profiling*
Monomers are nucleotides in DNA
56
What does each nucleotide consist of?
## Footnote
*IQ5: Investigate the use of technologies to determine inheritance patterns in a populations
using, for example – DNA sequencing and profiling*
* A phosphate group
* Pentose sugar molecule
* Nitrongenous base (A,T,G or C)
57
What happens when you heat DNA?
When you heat DNA it breaks (80-90 degree celsius).
Hydrogen bonds are weak.
58
How is DNA analysed and visualised?
## Footnote
*IQ5: Investigate the use of technologies to determine inheritance patterns in a populations
using, for example – DNA sequencing and profiling*
1. Extract pure DNA
2. Cut DNA with enzymes
3. Amplify fragments using PCR
4. Identify fragments via gel electrophoresis
5. (Optional) Reconstruct into a full genome
59
What are 4 key steps that led to the evolution of DNA technology?
## Footnote
*IQ5: Investigate the use of technologies to determine inheritance patterns in a populations
using, for example – DNA sequencing and profiling*
* Discovering DNA’s structure and chemical composition
* Understanding DNA replication’s role in genetic stability
* Understanding molecular events of protein synthesis
* Discovery of restriction enzymes that cut DNA into specific segments
60
What is DNA profiling?
DNA profiling comapres individuals by characteristics in small segments of their DNA, rather than sequencing the whole genome.
-Individuals who are more related have more similar DNA profiles.
61
What are short tandem repeats?
Short tandem repeats (STRs) are non-coding regions that consist of a repeating sequence *(e.g. TATAATATATATA).* The length of these repeats on different chromosomes is unique to each individual, giving rise to unique DNA profiles.
62
What does PCR do?
## Footnote
*IQ5: Investigate the use of technologies to determine inheritance patterns in a populations
using, for example – DNA sequencing and profiling*
PCR amplifies (copies) tiny amounts of DNA into over a billion copies for analysis.
63
Where is PCR used?
## Footnote
*IQ5: Investigate the use of technologies to determine inheritance patterns in a populations
using, for example – DNA sequencing and profiling*
* Medicine: Detect genetic disorders, cancer risk, prenatal screening, infectious agents
* Industry: When DNA is too scarce for analysis
* Research: Study receptors, drug binding, and evolutionary (phylogenetic) relationships
64
Describe the process of PCR
## Footnote
*IQ5: Investigate the use of technologies to determine inheritance patterns in a populations
using, for example – DNA sequencing and profiling*
1. DNA sample + primers + Taq polymerase + nucleotides added to PCR tube
2. Denaturation (95°C): DNA denatures (strands separate)
3. Annealing (50–60°C): Primers anneal (attach)
4. DNA synthesis (72°C): Taq polymerase synthesises new strands
5. Repeat for 30+ cycles → exponential DNA amplification
6. Clean up to remove unused materials
65
Is PCR an effective way of producing DNA?
Yes — produces over a billion copies in 1–2 hours and can target any DNA fragment using custom primers.
66
What is gel electrophoresis a form of? What’s its purpose?
It's a form of DNA sequencing used to separate DNA fragments by size to detect differences in DNA, such as mutations or genetic variation.
67
What differences in people does **gel electrophoresis** rely on?
It relies on variation in DNA sequences between individuals, which affects the location of restriction enzyme recognition sites, producing DNA fragments of different lengths.
68
What is agarose gel (+ Red-E-Vu), its function, and purpose?
Agarose gel: A jelly-like matrix with gaps of varying sizes that lets DNA fragments move based on size.
Red-E-Vu dye: Fluorescent dye that binds DNA and glows under UV light to make DNA fragments visible.
Purpose: To separate DNA clearly, ensure samples only move with the electric current, and avoid melting during the process.
69
What are buffer solutions used for in gel electrophoresis?
* Running buffer fills the tank, controls pH, and conducts electricity
* Keeps DNA negatively charged so it moves towards the positive terminal (anode)
70
What is the purpose of loading buffer?
A:
* Added to DNA samples
* Contains sucrose or glycerol to make the sample denser so it sinks into wells and can be tracked
71
What are the 2 types of buffer solutions?
A:
1. Running buffer (in tank – controls pH & conductivity)
2. Loading buffer (in samples – adds weight & tracking)
72
What are the 3 types of DNA samples used?
1. Standard Marker – known DNA fragment sizes for comparison
2. Control – contains only the target allele for testing
3. Sample – patient DNA (blood, normal tissue, tumour), amplified by PCR
73
# Gel electrophoresis
What is the purpose of the electrophoresis tank?
* Holds the gel and samples
* Connects to a power source (runs at 150 volts)
* Provides a controlled, safe environment
74
# Gel electrophoresis
What is a transilluminator (light box)?
* Shines UV light through the gel
* Makes Red-E-Vu-stained DNA fragments visible
75
What was the hypothesis for the experiment?
DNA analysis using gel electrophoresis can produce a pattern of DNA strands that show the presence of **normal or mutate P53 alleles** confirming a diagnosis of **Li-Fraumeni Syndrome**
76
What is a risk assessment?
A risk assessment identifies potential hazards in an experiment and outlines safety measures to minimise harm.
77
What factors affect the mobility of molecules in gel electrophoresis?
* Charge
* Size of molecule
* Shape of molecule
* Buffer conditions
* Gel concentration
* Voltage
78
What must wells be checked for?
✔ Ensure no damage to wells before loading
✔ Damaged wells can cause uneven migration and inaccurate results
79
How are pipettes used?
✔ Use pistol grip for precision
✔ Do not invert pipettes – prevents contamination of pipette pump and next sample
80
What are two key points when loading wells?
Ensure entire sample is transferred to prevent contamination of the next well
Sample must be evenly distributed for accurate, clear migration during gel run
81
Describe the process of gel electrophoresis. How do the molecules move?
Process:
1. Agarose gel is placed in a buffered salt solution to maintain pH.
2. DNA is mixed with a fluorescent dye.
3. Mixture is loaded into wells in the gel.
4. A standard DNA ladder (known fragment sizes) is also loaded.
5. Electric current is applied – DNA moves toward the positive terminal (anode) because of its negatively charged phosphate groups.
6. Shorter fragments move faster and further than longer fragments, creating separation.
7. UV light reveals the fluorescent DNA bands, which are then compared to the standard and control to interpret results.
82
What causes cancer?
## Footnote
*IQ2: Investigate the cause and host responses of non-infectious diseases in humans,
including cancer*
Cancer is a disease caused by uncontrallable cell growth.
83
Recall that mutations can either alter "---" function or "---" expression.
## Footnote
*IQ2: Investigate the cause and host responses of non-infectious diseases in humans,
including cancer*
Protein function
or
Gene expression
84
Do all mutations cause cancer? Which genes are involved when they do?
## Footnote
*IQ2: Investigate the cause and host responses of non-infectious diseases in humans,
including cancer*
No, not all mutations cause cancer.
Mutations that lead to uncontrolled cell divison affect one of **3 gene types**.
85
What are the **3 gene types** that if mutated can contribute to cancer by disrupting normal control of cell cycle?
## Footnote
*IQ2: Investigate the cause and host responses of non-infectious diseases in humans,
including cancer*
1. DNA repair genes
2. Proto-oncogenes
3. Tumour suppressor genes
86
What are DNA repair genes and what happens when they mutate?
## Footnote
*IQ2: Investigate the cause and host responses of non-infectious diseases in humans,
including cancer*
DNA repair genes code for enzymes that detect and repair DNA damage. If mutated, these enzymes fail to arrest the cell cycle, leading to uncontrolled cell division and increased cancer risk.
87
What are tumour suppressor genes and what do they do?
Tumour suppressor genes code for proteins that slow or stop cell growth and can trigger cell death when necessary.
88
What happens when tumour suppressor genes are mutated?
If both copies are mutated (a recessive effect), the cell loses control over growth inhibition, increasing cancer risk.
89
What is an example of a tumour suppressor gene?
P53 is a key tumour suppressor that regulates DNA repair and can induce apoptosis in damaged cells.
90
What are germline mutations and how are they tracked?
Germline mutations are inherited mutations present in the gametes. They are tracked using a pedigree and are more likely to appear among family members.
91
Are germline mutations more common than acquired mutations in cancer?
No, most cancers are caused by acquired (somatic) mutations. Germline mutations are rarer.
92
What is an example of an inherited cancer caused by a germline mutation?
Li-Fraumeni Syndrome, caused by a mutation in the P53 gene, is a familial cancer
93
94
What is the two-hit hypothesis?
It states that both alleles of a tumour suppressor gene (like P53) must be inactivated for cancer to develop. In Li-Fraumeni Syndrome, one allele is inherited as mutated (first hit), and a somatic mutation in the other allele (second hit) leads to cancer.
95
What are the diagnostic criteria for Li-Fraumeni Syndrome?
1. A tumour diagnosed before age 45
2. One first-degree relative with cancer before 45
3. A second close relative with cancer before 45
96
How is Li-Fraumeni Syndrome treated or prevented?
1. Genetic testing (PCR + gel electrophoresis) identifies P53 mutations
2. Pedigrees help detect at-risk relatives
3. Cancer screening for common cancers like breast, brain, leukemia, and colorectal
4. Genetic counselling supports patients and families emotionally and medically
97
What is the function of the pinna?
## Footnote
*IQ5: Explain a range of causes of disorders by investigating structures and functions of
relevant organs, for example: (2, onwards)
o Hearing loss
o Visual disorders
o Loss of kidney function*
Collects sound waves and channels them into the ear canal
98
What does the tympanic membrane (eardrum) do?
## Footnote
*IQ5: Explain a range of causes of disorders by investigating structures and functions of
relevant organs, for example: (2, onwards)
o Hearing loss
o Visual disorders
o Loss of kidney function*
Vibrates to transmit and amplify sound waves; separates outer and middle ear.
99
What is the role of the ear ossicles (malleus, incus, stapes)?
## Footnote
*IQ5: Explain a range of causes of disorders by investigating structures and functions of
relevant organs, for example: (2, onwards)
o Hearing loss
o Visual disorders
o Loss of kidney function*
Transfer vibrations from the tympanic membrane to the cochlea as pressure waves.
100
What does the Eustachian tube do?
Connects the ear to the nose/throat, equalises pressure, and drains fluid.
101
What is the function of the oval window?
Receives and transfers vibrations from the ossicles to the inner ear.
102
What is the purpose of the round window?
Releases inner ear pressure by expanding when the oval window is compressed, aiding cochlear vibration.
103
What does the cochlea do?
Receives and analyses sounds, with higher frequencies detected at the base and lower ones at the apex.
104
What is the function of the organ of Corti?
Contains hair cells (stereocilia) that transduce sound vibrations into nerve impulses.
105
What does the auditory nerve do?
Carries electrical impulses from the cochlea to the brain for sound perception.
106
What is sound?
Sound is caused by vibrations which move air particles in a longitudinal wave (move in the same direction as wave) which cause a series of compressions and refractions.
- travel faster through solid + liquid as the particles are closer together
107
What is wavelength?
The distance between one compression and the next in a sound wave.
108
What is frequency?
The number of sound waves passing a fixed point per second, measured in Hertz (Hz); higher frequency = higher pitch.
109
What is amplitude?
The maximum displacement of particles in a wave, determining loudness; measured in decibels (dB).
110
What is the period of a wave?
The time it takes for a particle to complete one full cycle of vibration.
111
How is sound energy converted in the ear?
Sound’s kinetic energy is turned into mechanical energy by the ossicles, then into electrochemical signals by hair cells in the cochlea for the auditory nerve.
112
What causes hearing loss?
Damage to one or more parts of the auditory system; the type and severity depend on the location and the sound frequencies affected.
113
What are the 3 types of hearing loss?
* Conductive hearing loss
* Sensorineural hearing loss
* Mixed Hearing loss
114
What is conductive hearing loss?
Where does it occur and how does it affect hearing?
* Occurs in the external or middle ear
* Caused by malformations, perforated eardrum, infections, damaged ossicles, or hardening of the stapes
* Hinders hearing by preventing effective transfer of sound vibrations to the inner ear
* Affects the volume of sound
115
What is sensorineural hearing loss? Where does it occur and how does it affect hearing?
* Occurs in the inner ear
* Caused by damage to hair cells or auditory nerve, often permanent
* Hinders the sensing or conversion of vibrations into nerve signals
* Affects both volume and clarity of sound
116
What is mixed hearing loss?
* Involves both conductive and sensorineural components
* Can affect multiple stages of the auditory pathway
* Includes auditory processing disorders where the brain misinterprets sounds
117
# eye parts
What is the function of the conjunctiva?
## Footnote
*Visual disorders*
Provides protection and lubrication by producing mucus and tears.
118
# Eye parts
What is the role of the sclera?
## Footnote
*Visual disorders*
The white eye of the eye that maintains shape and protects from injury.
119
# eye parts
What is the function of the cornea?
## Footnote
*Visual disorders*
Protects against infiltrates and UV radiation; performs 65%-75% of refraction in the eye.
120
# eye parts
What does the choroid do?
## Footnote
*Visual disorders*
Contains blood vessels that brign oxygen and nutrients to the eye.
121
# eye parts
What is the function of the ciliary body?
## Footnote
*Visual disorders*
Produces aqueous humour and contains muscles that adjust the shape of the lens.
122
# eye parts
What does the iris control?
## Footnote
*visual disorders*
Controls pupil size to regulate the amount of light entering the eye.
123
# eye parts
What is the role of the lens?
## Footnote
*visual disorders*
Refracts and focuses light onto the retina to create images.
124
# eye parts
What is the function of aqueous humour?
## Footnote
*visual disorders*
Maintains pressure within the eye.
125
# eye parts
What is purpose of the virteous humour?
## Footnote
*visual disorders*
Provides nutrients and helps maintain the eye's shape.
126
What does the retina do?
Captures incoming photons and converts them into electrical and chemical signals.
127
128
What is light?
## Footnote
*Visual disorders*
Wavelengths of energy within the visible spectrum (380–700 nm).
129
What is refraction?
## Footnote
*Visual disorders*
The bending of light as it passes through substances of different densities.
130
Where does refraction occur in the eye?
Cornea, aqueous humour, lens and vitreous humour.
131
Where does the greatest amount of refraction occur in the eye?
At the cornea.
132
What is accommodation in the eye?
The eye's ability to change the shape of the lens to focus on near or far objects.
133
How does the eye accomodate for near objects?
* Ciliary muscles contract
* Suspensory ligaments loosen
* Lens becomes more rounded
* More light is refracted
134
How does the eye accommodate for far objects?
* Ciliary muscles relax
* Suspensory ligaments tense
* Lens becomes more flat
* Minimum light is refracted
135
What is the light reflex?
The eye's automatic response to light levels by adjusting pupil size.
136
What happens to the pupil in bright light?
Iris sphincter muscles contract to constrict the pupil and protect photoreceptors.
137
What happens to the pupil in dim light?
Iris muscles relax, enlarging the pupil to allow more light in for vision.
138
What is hyperopia?
## Footnote
*Visual disorders*
Farsightedness
- Light is focused behind the retina producing blurry images.
- clear vision of far objects but blurry near vision
139
What is myopia?
## Footnote
*Visual disorders*
Short-sightedness
Cause: bulging cornea or elongated eyeball
Light focus: infront of retina.
140
What is astigmatism?
## Footnote
*Visual disorders*
Refractive error due to an irregular (asymmetrical) curve of the cornea or lens.
141
What is presbyopia?
## Footnote
*Visual disorders*
Age-related farsightedness
* cause: lens lose flexibility
* effect: light focuses behind the retina, causing blurry near vision
* Typical onset: 40s
142
What is cataracts?
## Footnote
*Visual disorders*
Clouding of the lens due to clumping of proteins.
Cause: Aging, lifestyle factors, or diseases like diabetes.
Effect: Obstructs light from reaching the retina, leading to blurred or dim vision.
143
What is macular degeneration?
Age-related deterioration of the macula (central part of the retina).
Effect: Loss of central vision, making tasks like reading or recognising faces difficult.
144
What is diabetic retinopathy?
Damage to retinal blood vessels caused by prolonged high blood glucose.
Effect: Oxygen deprivation, swelling, and haemorrhage in the retina.
Common in: People with uncontrolled diabetes.
145
What is glaucoma?
Damage to the optic nerve due to increased intraocular pressure.
Effect: Gradual loss of peripheral vision, and eventually central vision if untreated.
146
What is the cortex of the kidney?
## Footnote
*The kidney structure + function*
The outer layer containing Bowman’s capsules.
147
What is the medulla of the kidney?
## Footnote
*The kidney structure + function*
Inner region beneath the cortex where the loop of Henle is located.
148
What are renal pyramids?
## Footnote
*The kidney structure + function*
Inner region beneath the cortex where the loop of Henle is located.
149
What are renal pyramids?
## Footnote
*The kidney structure + function*
Triangular sections of kidney tissue containing cortex, medulla and nephrons.
150
What are small renal calices?
## Footnote
*The kidney structure + function*
Small drainage structures around the apex of the pyramid that collect urine.
151
What are large renal calyces?
## Footnote
*The kidney structure + function*
Formed by the merging of 2–3 small calices to channel urine to the renal pelvis.
152
What is the renal pelvis?
## Footnote
*The kidney structure + function*
Funnel-shaped structure that collects urine and passes it to the ureter.
153
What is the function of the renal artery?
## Footnote
*The kidney structure + function*
Brings unfiltered, oxygenated blood to the kidney.
154
What is the function of the renal vein?
## Footnote
*The kidney structure + function*
Carries filtered blood away from the kidney.
155
What is the function of the ureter?
Carries urine from the kidney to the bladder.
156
What is the nephron's role?
(functional unit)
Nephrons are the functional units of kidneys.
Filters blood to form urine while reabsorbing useful substances.
157
What is the glomerulus?
Capillary network that filters small molecules like water and NaCl into Bowman’s capsule; large molecules stay in the blood.
158
What is Bowman’s capsule?
Surrounds the glomerulus and collects the filtered small molecules (filtrate).
159
What happens in the proximal tubule?
Reabsorbs about 65% of the filtrate, including glucose, salts, and water.
160
What is the function of the loop of Henle?
Reabsorbs water and sodium to conserve water and concentrate urine.
161
What happens in the distal tubule?
Regulates water, electrolytes, and pH to maintain homeostasis.
162
What is the function of the collecting duct?
Collects urine from multiple nephrons and directs it to the renal pelvis.
163
Where does damage usually occur in kidney disease?
## Footnote
*Kidney disorders*
The nephrons
164
Effect of kidney failure on the excretory system:
Inability to remove waste, regulate salts, and balance water
Waste and fluid accumulate in the body, disrupting homeostasis
165
Common Symptoms of Kidney Failure (4):
Swelling in ankles and feet (fluid retention)
Chest pain (fluid build-up around the heart lining)
Shortness of breath (fluid in lungs)
High blood pressure (due to fluid overload and hormone imbalance)
