LAST YR 11 EXAM - BIO

Stages of Mitosis

Prophase → Metaphase → Anaphase → Telophase → (Cytokinesis)

Prophase

• Chromosomes condense and become visible.

• Nuclear membrane breaks down.

• Spindle fibres begin to form.

Metaphase

• Chromosomes line up at the equator.

• Spindle fibres attach to centromeres.

Anaphase

• Sister chromatids separate.

• They are pulled to opposite poles.

Telophase

• Chromatids arrive at poles.

• Nuclear membranes reform.

• Chromosomes decondense.

Cytokinesis

• Cytoplasm divides.

• Two identical daughter cells form.

Genotype

The genetic makeup (e.g., Bb).

Phenotype

The physical trait expressed (e.g., brown eyes).

Homozygous

Two identical alleles (BB or bb).

Heterozygous

Two different alleles (Bb).

Dominant Gene

Expressed when present.

Recessive Gene

Only expressed in homozygous recessive (bb).

Genotype Ratio

2 Bb : 2 bb → 1:1

Phenotype Ration

50% dominant : 50% recessive → 1:1

Pedigree symbols

• Circle = Female

• Square = Male

• Shaded shape = affected

Autosomal Dominant Inheritance

• Every generation.

• Affected individuals have at least one affected parent.

• Males & females equally affected.

Autosomal Recessive Inheritance

• Skips generations.

• Two unaffected parents can have an affected child.

X-Linked Recessive Inheritance

• More males affected.

• Affected sons often have carrier mothers.

• No father-to-son transmission.

X-Linked Dominant Inheritance

• All daughters will possess their father’s genes

• No Sons affected bythe father

• Approx. Half affected

Y-linked Inheritance

• All males, no females

PCR Stage 1

Denaturation, 95°C, Hydrogen bonds are broken, DNA becomes single-stranded

PCR Stage 2

Annealing, 55°C, Primers attach to the single strand of DNA

PCR Stage 3

Extending, 72°C, Primers begin building complementry strands with nucleotides

Purpose of PCR

The purpose of PCR is to amplify (make many copies of) a specific segment of DNA

Restriction Enzymes

Restriction enzymes, or restriction endonucleases, are molecular scissors that cut DNA at specific, short sequences known as restriction sites.

Sticky Ends

Staggered cuts → overhangs (e.g., EcoRI).

Blunt Ends

Straight across cuts (e.g., SmaI).

Role of Gel Electrophroesis

To separate DNA fragments by size.

Gel Electrophroesis Diagram

Nuclear Transfer Cloning

Cloning technique, dolly the sheep

SCNT Stages

• Remove nucleus from an egg cell (enucleation).

• Remove nucleus from somatic cell of organism to be cloned.

• Insert somatic nucleus into enucleated egg.

• Apply electric shock → stimulates division.

• Embryo grows to group of 16 cells, morula

• Implant into surrogate.

• Surrogate gives birth to clone.

Consequentialism

• Right/wrong determined by outcomes.

• “Does it maximise good or minimise harm?”

Duty-Based

• Right/wrong based on rules, duties, rights.

• “Some actions are always wrong regardless of outcome.”

Virtue-Based

• Focus on moral character.

• “What would a good person do?”

Role of Circulatory System

1. Transport water, oxygen and carbon dioxide

2. Carry nutrients and remove wastes

3. Maintain a constant body temperature

4. Circulate hormones

Circulatory System Diagram

Blood

Made up of Plasma, Erythrocytes, Leukocytes, and Platelets

Erthorocytes

• Carries ocygen attached to haemoglobin molecules

• No Nucleus

• Biconcave shaoe to increase SA

Leukocytes

• Defend the body by removing debris and producing antibodies

Platelets

• Aids blood clotting

Arteries

• Thick elastic walls

• high blood pressure as they are close to the heart

• Carries blood away from the heart

The main arteries are the Aorta, which sends oxygenated blood to the body and the Pulmonary Artery, which sends deoxygenated blood to the lungs to be oxygenated

Veins

• Thinner walls

• Valves

• Not easily stretched

• Carries blood towards the heart

• Decreased blood pressure

The main veins are the Vena Cavae, which carries deoxygenated blood from the body to the right atrium, and the Pulmonary Vein, which carries oxygenated blod to the left atrium.

Capillaries

• Very thin walls

• Highly branched and narrow

• Link arteries with veins

• Essential for the exchange of materials between blodd and other body cells.

Heart

• Pump that keeps blood flowing

• 4 chambered (2 atria, 2 ventricles) and valves to keep blood seperate

• Right side pumps deoxygenated blood into the pulmonary

• Left side sends blood into the aorta

Valves

• Stops backflow of blood

• 4 valves in heart

• 2 semilunar valves between ventricles and outgoing arteries

• Tricuspid valve between right atrium and ventricle

• Bicuspid valve between left atrium and ventricle

Independent Variable

What you change.

Dependant Variable

What you measure.

Controlled Variable

Kept constant.

Precision

How close repeated measurements are to each other.

Accuracy

How close your measurements are to the true value.

Reliability

Consistency of results → repeat trials increase reliability.

Validity

Whether the experiment tests what it is supposed to.

Random Errors

• Unpredictable variations (e.g., timing reaction slightly off).

• Reduced by repeating trials.

Systematic Errors

• Bias that shifts results the same way each time (e.g., faulty scale).

• Reduced by calibrating equipment.

Personal Errors

• Mistakes, not true scientific errors.

• E.g., reading equipment wrong.

Right Atrium

Receives deoxygenated blood from the body via the vena cava

Left Atrium

Receives oxygenated blood from the lungs via the pulmonary vein

Right Ventricle

Pumps deoxygnated blood to the lungs, via the pulmonary artery

Left Ventricle

Pumps oxygenated blood to the body, via the aorta