1
Q
What name is given to the small molecular subunits that join together to form larger biological molecules?
A
Monomers
Small repeating building blocks that can be chemically joined to form larger molecules.
2
Q
What term describes a large molecule formed when many repeating subunits are chemically bonded together?
A
Polymer
Polymers consist of many monomers linked in long chains or complex structures.
3
Q
Glucose and other simple sugars belong to which class of biological monomer?
A
Monosaccharides
These single sugar units can combine to form disaccharides and polysaccharides.
4
Q
Which type of monomer joins together to form proteins?
A
Amino acids
Amino acids link via peptide bonds during protein synthesis.
5
Q
DNA and RNA are built from repeating units known as what?
A
Nucleotides
Each nucleotide contains a sugar, phosphate group, and nitrogen-containing base.
6
Q
What type of reaction joins two molecules together while releasing a molecule of water?
A
Condensation reaction
Also called a dehydration reaction, it commonly forms glycosidic, peptide, and ester bonds.
7
Q
Fill in the blank:
A condensation reaction forms a chemical bond between molecules and releases a molecule of _______.
A
Water
Water is removed when the bond forms between the monomers.
8
Q
What type of reaction breaks a bond between two molecules using a molecule of water?
A
Hydrolysis
The reverse of condensation; it is common in digestion of biological polymers.
9
Q
True or False:
Hydrolysis reactions build polymers from monomers.
A
False
Hydrolysis breaks polymers into smaller units; condensation builds them.
10
Q
What class of biological molecule includes sugars, starch and glycogen?
A
Carbohydrates
Carbohydrates are organic molecules composed of carbon, hydrogen and oxygen, often used for energy storage or structural roles.
11
Q
What type of monomer forms larger carbohydrate molecules?
A
Monosaccharides
Monosaccharides are single sugar units that act as building blocks for disaccharides and polysaccharides.
12
Q
Name three common monosaccharides found in biological systems.
A
- Glucose
- Galactose
- Fructose
These are hexose sugars with the same molecular formula but slightly different structures.
13
Q
What type of chemical bond forms when two monosaccharides join together?
A
Glycosidic bond
This bond forms during a condensation reaction between two sugar molecules.
14
Q
Fill in the blank:
Two monosaccharides join together through a _______ reaction to form a glycosidic bond.
A
Condensation
The reaction removes a molecule of water as the bond forms.
15
Q
What carbohydrate is produced when two glucose molecules join together?
A
Maltose
Maltose is a disaccharide commonly produced during starch digestion.
16
Q
Which disaccharide forms when glucose combines with fructose?
A
Sucrose
Sucrose is the main sugar transported in the phloem of plants.
17
Q
Which disaccharide is formed from glucose and galactose?
A
Lactose
Lactose is the sugar found in milk.
18
Q
Glucose exists in two structural forms known as what?
A
Isomers
The two forms are α-glucose and β-glucose, which differ in the arrangement of atoms around one carbon.
19
Q
What two specific structural forms of glucose exist in solution?
A
- α-glucose
- β-glucose
They differ in the orientation of the hydroxyl group on carbon 1.
20
Q
What term describes carbohydrates formed by many glucose units joined together?
A
Polysaccharides
These are large polymer molecules built from many monosaccharides.
21
Q
Which two polysaccharides are formed from α-glucose in living organisms?
A
Starch and glycogen
Both are energy storage molecules in plants and animals respectively.
22
Q
Which polysaccharide is formed from β-glucose?
A
Cellulose
Cellulose forms strong fibres used in plant cell walls.
23
Q
What is the main storage carbohydrate in animals?
A
Glycogen
Glycogen is stored mainly in the liver and muscles and can be rapidly broken down to release glucose.
24
Q
What is the main storage carbohydrate in plants?
A
Starch
Starch is stored in plant cells and consists of amylose and amylopectin molecules.
25
What is the main **structural carbohydrate** found in **plant cell walls**?
Cellulose
## Footnote
Cellulose forms strong microfibrils that provide structural support to plant cells.
26
Which **reagent** is used to test for **reducing sugars**?
Benedict's solution
## Footnote
When heated to near boiling (≈95 °C) with a reducing sugar, the solution changes from blue to green, yellow, orange or brick-red depending on the concentration of reducing sugar.
27
What **colour change** occurs when **Benedict's test** gives a positive result for reducing sugars?
Blue to brick-red precipitate
## Footnote
The colour may vary depending on sugar concentration.
28
How can a **non-reducing sugar** be tested using **Benedict's solution**?
Hydrolysis
## Footnote
The sugar is first hydrolysed with dilute acid, neutralised, then tested with Benedict’s solution.
29
Which **reagent** is used to test for **starch**?
Iodine solution
## Footnote
Iodine/potassium iodide turns from brown/orange to blue-black in the presence of starch.
30
# True or False:
**Glycogen** is the main **storage carbohydrate** in plants.
False
## Footnote
Plants store carbohydrates mainly as starch, while animals store glycogen.
31
# Fill in the blank:
**Iodine solution** turns _\_\_\_\_\_\_ in the presence of **starch**.
Blue-black
## Footnote
This colour change is used in qualitative food tests for starch.
32
Which two major **groups of biological lipids** are required in the **AQA specification**?
Triglycerides and phospholipids
## Footnote
Both are important biological lipids but have different structures and functions in organisms.
33
What type of **molecule** combines with **fatty acids** to form triglycerides?
Glycerol
## Footnote
Glycerol is a three-carbon alcohol that forms the backbone of triglycerides.
34
How many **fatty acid molecules** are present in one **triglyceride molecule**?
Three
## Footnote
Each fatty acid attaches to glycerol via an ester bond.
35
# Fill in the blank:
A **triglyceride** forms when one **glycerol molecule** reacts with three _\_\_\_\_\_\_ molecules.
Fatty acid
## Footnote
This occurs through condensation reactions.
36
What type of **chemical bond** forms between **glycerol and fatty acids** in triglycerides?
Ester bond
## Footnote
Each ester bond forms during a condensation reaction that releases water.
37
# Fill in the blank:
An **ester bond** forms between **glycerol** and a **fatty acid** during a _\_\_\_\_\_\_ reaction.
Condensation
## Footnote
Water is released when the ester bond forms.
38
What term describes a **fatty acid** that contains no **carbon–carbon double bonds**?
Saturated
## Footnote
Saturated fatty acids contain the maximum number of hydrogen atoms.
39
What term describes a **fatty acid** that contains one or more **carbon–carbon double bonds**?
Unsaturated
## Footnote
Double bonds introduce bends in the fatty acid chain.
40
# True or False:
**Unsaturated fatty acids** contain at least one **carbon–carbon double bond**.
True
## Footnote
These double bonds affect the shape and physical properties of the lipid.
41
In **phospholipids**, what **group** replaces one of the fatty acids found in a triglyceride?
Phosphate group
## Footnote
This substitution creates a molecule with different chemical properties.
42
Which **lipid type** is a major component of **cell membranes**?
Phospholipids
## Footnote
Their structure allows them to form bilayers in aqueous environments.
43
Which **lipid type** is primarily used for **long-term energy storage** in organisms?
Triglycerides
## Footnote
They have a high energy content and are stored in adipose tissue in animals.
44
Why are **triglycerides** good **energy storage molecules**?
They have high energy content.
## Footnote
They contain many C–H bonds and are insoluble, so they do not affect water potential.
45
Why are **phospholipids** suited to forming **cell membranes**?
They are amphipathic.
## Footnote
They have a hydrophilic phosphate head and hydrophobic fatty acid tails.
46
What **qualitative test** is used to detect **lipids** in a food sample?
Emulsion test
## Footnote
The test uses ethanol and water to detect lipids.
47
# Fill in the blank:
A **positive emulsion test** for **lipids** produces a _\_\_\_\_\_\_ white emulsion.
Milky
## Footnote
Lipids dissolve in ethanol and form a cloudy emulsion when water is added.
48
What **reagent** is first added to a sample during the **emulsion test for lipids**?
Ethanol
## Footnote
The mixture is shaken and then water is added to observe the emulsion.
49
What type of biological **monomer** joins together to form **proteins**?
Amino acids
## Footnote
Proteins are polymers formed from chains of amino acids linked together.
50
What **functional group** is represented by **NH₂** in the general structure of an amino acid?
Amine group
## Footnote
This basic group contains nitrogen and can accept a hydrogen ion.
51
What **functional group** is represented by **COOH** in an amino acid?
Carboxyl group
## Footnote
This acidic group can donate a hydrogen ion in solution.
52
# Fill in the blank:
The part of an amino acid that differs between different **amino acids** is the \_\_\_\_\_\_ **group**.
R group
## Footnote
The R group (side chain) determines the chemical properties of the amino acid.
53
What type of **bond** forms when two **amino acids** join together?
Peptide bond
## Footnote
This bond forms during a condensation reaction between the amine group of one amino acid and the carboxyl group of another.
54
# Fill in the blank:
A \_\_\_\_\_\_ **reaction** occurs when two **amino acids** join to form a peptide bond.
Condensation
## Footnote
A molecule of water is released when the bond forms.
55
What **molecule** is formed when two **amino acids** join together?
Dipeptide
## Footnote
A dipeptide contains two amino acids linked by one peptide bond.
56
What name is given to a long chain of many **amino acids** joined together?
Polypeptide
## Footnote
Polypeptides may fold to form functional proteins.
57
A functional **protein** may consist of one or more what type of **chain**?
Polypeptides
## Footnote
Some proteins contain multiple polypeptide subunits.
58
What level of **protein structure** refers to the **sequence of amino acids** in a polypeptide chain?
Primary structure
## Footnote
The order of amino acids is determined by the DNA sequence.
59
What level of **protein structure** forms when a polypeptide chain coils into an **α-helix** or folds into a **β-pleated sheet**?
Secondary structure
## Footnote
Stabilised mainly by hydrogen bonds between peptide bonds in the backbone.
60
What level of **protein structure** describes the overall **three-dimensional folding** of a polypeptide?
Tertiary structure
## Footnote
Stabilised by hydrogen bonds, ionic bonds and disulfide bridges between R groups.
61
What level of **protein structure** occurs when multiple **polypeptide chains** combine to form a functional protein?
Quaternary structure
## Footnote
Examples include haemoglobin, which contains multiple polypeptide subunits.
62
Which type of **bond** forms between **sulfur atoms** in some amino acid side chains?
Disulfide bridge
## Footnote
These strong covalent bonds help stabilise the tertiary structure of proteins.
63
Which type of **bond** forms between **oppositely charged side chains** in proteins?
Ionic bonds
## Footnote
These interactions contribute to stabilising tertiary structure.
64
Which relatively weak **bonds** help stabilise both **secondary and tertiary protein structures**?
Hydrogen bonds
## Footnote
Many hydrogen bonds together help maintain protein shape.
65
Why is **protein structure** important for **protein function**?
They have a specific shape.
## Footnote
The precise 3D structure determines how the protein interacts with other molecules.
66
What **chemical test** is used to detect **proteins** in a sample?
Biuret test
## Footnote
The test detects peptide bonds present in proteins.
67
# Fill in the blank:
A positive **Biuret test** changes the **solution** from blue to \_\_\_\_\_\_.
Purple
## Footnote
The colour change indicates the presence of peptide bonds in proteins.
68
# True or False:
All **proteins** consist of only one **polypeptide chain**.
False
## Footnote
Many proteins contain multiple polypeptide chains forming quaternary structure.
69
What type of **biological molecule** acts as a **catalyst** in living organisms?
Enzymes
## Footnote
Enzymes are proteins that speed up biochemical reactions without being used up.
70
What effect does an **enzyme** have on the **activation energy** of a reaction?
Lowers activation energy
## Footnote
By lowering activation energy, enzymes increase the rate of reactions.
71
What model describes how **enzyme active sites** change shape to fit a **substrate** during binding?
Induced-fit model
## Footnote
The active site becomes more complementary to the substrate as binding occurs.
72
What region of an **enzyme** binds to the **substrate** during a reaction?
Active site
## Footnote
The active site has a specific tertiary structure that allows substrate binding.
73
# Fill in the blank:
When a **substrate** binds to an **enzyme**, an _\_\_\_\_\_\_ complex is formed.
Enzyme-substrate complex
## Footnote
This temporary complex allows the reaction to occur more easily.
74
Why are enzymes considered highly **specific**?
They have an active site with a complementary shape which is coded for by the specific sequence of amino acids.
## Footnote
The shape of the active site only fits particular substrates.
75
# True or False:
Each **enzyme** usually catalyses only **one specific reaction**.
True
## Footnote
Enzyme specificity arises from the precise structure of the active site.
76
What happens to the **rate** of an **enzyme-controlled reaction** when enzyme concentration increases (if substrate is abundant)?
Increases
## Footnote
More enzyme molecules mean more available active sites.
77
How does increasing **substrate concentration** affect the **rate** of an enzyme-controlled reaction?
Increases, then plateaus.
## Footnote
The rate rises until all enzyme active sites become occupied.
78
What type of **inhibitor** competes with the **substrate** for the active site of an enzyme?
Competitive inhibitor
## Footnote
These inhibitors have a similar shape to the substrate.
79
What type of **inhibitor** binds to an enzyme at a site other than the **active site**?
Non-competitive inhibitor
## Footnote
This binding alters the enzyme's shape and reduces its activity.
80
How does a **competitive inhibitor** affect **enzyme activity**?
Competes with the substrate.
## Footnote
It reduces reaction rate by blocking substrate binding to the active site.
81
How does a **non-competitive inhibitor** affect **enzyme activity**?
Alters the shape of the active site.
## Footnote
This prevents the substrate from binding effectively.
82
Why does **temperature** affect **enzyme-controlled reactions**?
It changes kinetic energy and enzyme structure.
## Footnote
High temperatures can denature enzymes by breaking bonds that maintain their tertiary structure.
83
What happens to an **enzyme** when it becomes **denatured**?
Active site changes shape.
## Footnote
The substrate can no longer bind, so the enzyme stops functioning.
84
Why does **pH** affect **enzyme activity**?
It alters bonds that maintain enzyme structure.
## Footnote
Changes in pH can disrupt bonds that maintain the enzyme’s tertiary structure.
85
What formula can be used to calculate **pH** from **hydrogen ion concentration**?
pH = −log10[H⁺]
## Footnote
This logarithmic relationship shows that small changes in pH represent large changes in H⁺ concentration.
86
What practical **investigation** is commonly used to study **enzymes** in AQA Biology?
Enzyme rate investigation
## Footnote
Students measure how changing a variable affects the rate of an enzyme-controlled reaction.
87
What **mathematical method** can be used to determine the **initial rate** of an enzyme reaction from a graph?
Tangent method
## Footnote
A tangent drawn at the start of the curve allows calculation of the initial rate.
88
What type of biological molecule carries **genetic information** in almost all living cells?
DNA
## Footnote
Stores hereditary information and forms chromosomes in eukaryotic cells.
89
Which molecule carries genetic instructions from **DNA** to **ribosomes** during protein synthesis?
mRNA
## Footnote
Acts as an intermediary between DNA and ribosomes.
90
What type of **macromolecule** are both **DNA and RNA** classified as?
Polynucleotides
## Footnote
They are long chains of repeating nucleotide monomers.
91
What is the **monomer unit** that builds both **DNA and RNA polymers**?
Nucleotide
## Footnote
Each nucleotide consists of a pentose sugar, phosphate group and nitrogen-containing base.
92
What three **components** make up a **nucleotide**?
* Pentose sugar
* Phosphate group
* Nitrogen-containing base
## Footnote
These components form the basic unit of nucleic acids.
93
Which **pentose sugar** is present in **DNA nucleotides**?
Deoxyribose
## Footnote
Deoxyribose lacks one oxygen atom compared with ribose.
94
Which **pentose sugar** is present in **RNA nucleotides**?
Ribose
## Footnote
Ribose contains one more oxygen atom than deoxyribose.
95
Which four **organic bases** occur in **DNA nucleotides**?
* Adenine
* Cytosine
* Guanine
* Thymine
## Footnote
Often abbreviated as A, C, G and T.
96
Which **organic base** is found in **RNA instead of thymine**?
Uracil
## Footnote
RNA contains A, C, G and U.
97
What type of **reaction** joins two **nucleotides** together when forming a nucleic acid polymer?
Condensation reaction
## Footnote
Water is released during the formation of the bond.
98
What is the name of the **covalent bond** formed between **nucleotides** in DNA and RNA chains?
Phosphodiester bond
## Footnote
Forms between the phosphate group of one nucleotide and the sugar of another.
99
What is the overall **three-dimensional shape** of a **DNA molecule**?
Double helix
## Footnote
Two polynucleotide strands twist around each other.
100
What type of **bond** holds the two **DNA strands** together?
Hydrogen bonds
## Footnote
These occur between complementary bases.
101
How are **bases paired** between the two **DNA strands**?
Complementary base pairing
## Footnote
Adenine pairs with thymine and cytosine pairs with guanine.
102
# True or False:
**DNA** consists of two **polynucleotide chains** that twist to form a double helix.
True
## Footnote
The strands run in opposite directions and are joined by hydrogen bonds.
103
# True or False:
**RNA** usually forms a long **double-stranded helix** like DNA.
False
## Footnote
RNA is usually a shorter single polynucleotide chain.
104
What **structure in cells** is made partly from **RNA** and is responsible for protein synthesis?
Ribosome
## Footnote
Ribosomes consist of ribosomal RNA (rRNA) and proteins.
105
# Fill in the blank:
A **DNA molecule** consists of two \_\_\_\_\_\_ chains held together by **hydrogen bonds** between bases.
Polynucleotide
## Footnote
Each chain is made from many nucleotides joined by phosphodiester bonds.
106
Why did early scientists doubt that **DNA** carried **genetic information**?
DNA appeared too simple.
## Footnote
DNA has only four bases and a repeating structure, appearing too simple to encode complex information.
107
If **30% of the bases** in a **DNA strand** are adenine, what percentage must be thymine?
30%
## Footnote
Complementary base pairing means A pairs with T in equal proportions.
108
How does **DNA replication** ensure that **genetic information** is maintained when a cell divides?
Semi-conservative replication
## Footnote
Each daughter DNA molecule contains one original strand and one newly synthesised strand.
109
What type of **structure** must be unwound at the start of **DNA replication**?
Double helix
## Footnote
The two antiparallel polynucleotide strands must separate so their bases can be copied.
110
Which enzyme separates the two **DNA strands** during replication by breaking the **bonds between bases**?
DNA helicase
## Footnote
This enzyme unwinds the helix and breaks hydrogen bonds between complementary bases.
111
What type of **bond** between complementary bases must be broken to separate the **DNA strands**?
Hydrogen bonds
## Footnote
These weak bonds hold base pairs together between the two strands.
112
During replication, exposed bases on the original strand attract free nucleotides according to which **rule** of **base pairing**?
Complementary base pairing
## Footnote
Adenine pairs with thymine and cytosine pairs with guanine.
113
# Fill in the blank:
Free DNA nucleotides align with bases on the original strand because it acts as a \_\_\_\_\_\_.
Template strand
## Footnote
Each original strand guides the order of nucleotides in the new strand.
114
Which enzyme joins adjacent nucleotides together to build the **new DNA strand** during **DNA replication**?
DNA polymerase
## Footnote
It catalyses the formation of phosphodiester bonds during strand synthesis.
115
What type of **reaction** joins neighbouring nucleotides together during **DNA replication**?
Condensation reaction
## Footnote
A molecule of water is released when the sugar-phosphate backbone forms.
116
# True or False:
Each **new DNA molecule** formed after replication contains **two completely new strands**.
False
## Footnote
Each DNA molecule contains one original strand and one newly synthesised strand.
117
What process occurs when the **DNA strands separate** and the **helix opens** up during replication?
DNA unwinding
## Footnote
This step allows the bases to become exposed for complementary pairing.
118
# Fill in the blank:
The enzyme that builds the new strand forms bonds between nucleotides to create the **sugar-phosphate** \_\_\_\_\_\_.
Backbone
## Footnote
The backbone consists of alternating deoxyribose sugars and phosphate groups.
119
Which classic experiment provided strong evidence supporting the **Watson–Crick model** of **DNA replication**?
Meselson–Stahl experiment
120
What property of water allows many **biochemical reactions** to occur in a **liquid medium**?
Water is a **solvent**.
## Footnote
Polar water molecules dissolve ions and polar molecules, enabling metabolic reactions in solution.
121
Which type of reaction joins two **biological molecules** together with the removal of a water molecule?
Condensation reaction
## Footnote
Forms bonds between monomers when polymers such as proteins, carbohydrates, and lipids are built.
122
What reaction breaks a chemical bond in a biological molecule using a molecule of water?
Hydrolysis reaction
## Footnote
Common in digestion and when polymers are broken into monomers.
123
# True or False:
Water directly participates as a **reactant** in many **metabolic reactions** inside cells.
True
## Footnote
Water acts as a metabolite in reactions such as hydrolysis and condensation.
124
Water resists rapid temperature change in cells and organisms. Which property of water is responsible for this **buffering effect**?
High specific heat capacity
## Footnote
A large amount of energy is required to change the temperature of water.
125
# True or False:
Water has a low specific heat capacity, allowing cells to heat and cool very rapidly.
False
## Footnote
Its relatively high specific heat capacity stabilises temperature in cells and aquatic environments.
126
A large amount of energy is required to convert water from liquid to vapour. What property of water does this describe?
Latent heat of vaporisation
## Footnote
This allows evaporation (e.g., sweating or transpiration) to remove heat efficiently.
127
# Fill in the blank:
Evaporation of water from a surface removes heat because water has a large _\_\_\_\_\_\_ heat of vaporisation.
latent
## Footnote
High energy is needed to break hydrogen bonds between water molecules.
128
Attraction between water molecules allows continuous columns of water to move through plant transport tissues. What property causes this **attraction**?
Cohesion
## Footnote
Hydrogen bonding between water molecules produces strong intermolecular attraction.
129
What property of water creates a tight surface layer where water meets air?
Surface tension
## Footnote
Produced by cohesive forces between water molecules at the surface.
130
# True or False:
**Cohesion** between water molecules helps maintain continuous columns of water in the xylem of plants.
True
## Footnote
Important for maintaining the transpiration stream.
131
# Fill in the blank:
The concentration of _\_\_\_\_\_\_ ions affects the **pH** of a solution.
hydrogen
## Footnote
pH is determined by the concentration of hydrogen ions in a solution.
132
Which ion is an essential component of **haemoglobin**?
Iron
## Footnote
Fe2+ ions bind oxygen in haemoglobin molecules.
133
What role do **sodium ions** play in nutrient absorption?
Co-transport
## Footnote
Sodium ions help transport glucose and amino acids into cells via co-transport mechanisms.
134
Which ion is a structural component of both **DNA** and **ATP**?
Phosphate
## Footnote
Phosphate groups form the backbone of DNA and are part of ATP molecules storing energy.
135
# True or False:
**Iron ions** are involved in the transport of oxygen in blood.
True
## Footnote
Fe2+ in haemoglobin reversibly binds oxygen for transport in red blood cells.
136
# True or False:
**Sodium ions** are only used in nerve impulses, not in nutrient absorption.
False
## Footnote
Sodium ions are crucial for co-transport of glucose and amino acids in epithelial cells.
137
How do **phosphate ions** contribute to **energy transfer**?
ATP formation
## Footnote
Phosphate groups in ATP store and release energy when bonds are broken and reformed.
138
# Fill in the blank:
High concentrations of _\_\_\_\_\_\_ ions in cytoplasm can lower the **pH**.
hydrogen
## Footnote
An increase in H+ ions makes the cytoplasm more acidic.
A-Level Biology (OCR B - MEI)
flashcards
Decks in class (27)
# Cards
-
1: Biological Molecules138
-
1: Enzymes & Digestion16
-
1: Cell Structure52
-
1: Cell Division20
-
1: Membranes & Transport20
-
2: Exchange & Transport Systems76
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2: Plant Transport20
-
2: Immunology36
-
3: DNA & Protein Synthesis27
-
3: Genetic Diversity14
-
3: Biodiversity & Classification32
-
3: Investigating Diversity12
-
4: Evolution42
-
4: Populations & Ecosystems24
-
4: Energy & Nutrient Cycles35
-
5: Photosynthesis23
-
5: Respiration17
-
5: ATP & Energy Transfer11
-
6: Homeostasis57
-
6: Nervous Coordination53
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6: Stimuli & Response62
-
6: Muscles14
-
7: Inheritance12
-
7: Populations (Hardy–Weinberg)15
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8: Gene Mutations & Expression58
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8: Gene Technologies46
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8: Disease24
