sample 1 bio

Where does transcription take place in a eukaryotic cell?

Nucleus

What enzyme catalyses the formation of mRNA during transcription?

RNA polymerase

What are the RNA base-pairing rules during transcription?

A with U, T with A, C with G, and G with C

Why are conceptual or physical models used in biology?

To help understand or predict biological processes, structures or systems

What is an enzyme?

a 3D selective biological catalyst made of protein

Give an example of an enzyme, its substrate and product.

Amylase breaks down starch into maltose

What is the induced fit model?

The substrate binds to the active site causing it to change shape slightly for a perfect fit before products are released

What is a polypeptide?

A long chain of amino acids

Where are polypeptides folded in the cell?

Rough Endoplasmic Reticulum

Give an example of a structural protein and where it is found.

Collagen in skin

Give a source, role and deficiency disease of Vitamin C.

citrus fruits, collagen formation, scurvy

Why are water-soluble vitamin supplements usually unnecessary on a balanced diet?

Excess water-soluble vitamins are excreted in urine and cannot be stored

What phase occupies most of the cell cycle and what happens to DNA during it?

Interphase, where DNA replication occurs

What is the difference between mitosis and meiosis?

Mitosis produces identical cells for growth and repair while meiosis produces gametes with half the chromosome number

What is the order of the stages of mitosis?

Prophase, Metaphase, Anaphase, Telophase

What is cytokinesis?

Division of the cytoplasm after nuclear division

Why do bacteria not undergo mitosis?

They have no nucleus and divide by binary fission

What is a mutation and how is it linked to cancer?

a change in DNA sequence or structure that can cause uncontrolled cell division forming tumours

What is the function of red blood cells and where are they produced?

They transport oxygen and are produced in the bone marrow

State two adaptations of red blood cells.

Biconcave shape increases surface area and no nucleus leaves more space for haemoglobin

Why do red blood cells only live for about 120 days?

They cannot repair themselves because they lack a nucleus and organelles

What happens during an incompatible blood transfusion?

Antibodies attack foreign antigens causing agglutination and haemolysis

Why is Rhesus factor important during pregnancy?

A Rhesus-negative mother carrying a Rhesus-positive fetus may develop complications

Why must carbon dioxide be excreted constantly?

It is a waste product of respiration and lowers blood pH if it builds up

Describe the mechanism of exhalation.

The diaphragm and intercostal muscles relax, thoracic volume decreases, pressure increases and air is forced out

State one digestive and two non-digestive functions of the liver.

Digestive: bile production, Non-digestive: deamination and detoxification

What is the hepatic portal vein and its function?

A blood vessel carrying nutrients from the intestine to the liver for regulation

What stain is used when preparing onion epidermal cells?

Iodine stain

How should a coverslip be lowered onto a microscope slide?

At a 45-degree angle to avoid air bubbles

How do you focus a microscope on high power?

Use only the fine focus knob