Exam Cards - Topic 2

Question 1

What is cystic fibrosis?

Answer 1

A genetic disease which causes the mucus which lines the lungs to dry and thicken, causing respiratory problems.

Question 2

What is the function of mucus in the lungs?

Answer 2

It traps dust, debris, and micro-organisms that enter the lungs. The cilia lining the lungs then remove them.

Question 3

Which two major effects does cystic fibrosis have on health?

Answer 3

It increases the chance of lung infections and makes gas exchange less efficient.

Question 4

Which kind of epithelium lines the alveoli and capillaries, and why?

Answer 4

Squamous/pavement epithelium because it can be less than 2μm thick, allowing for efficient diffusion.

Question 5

Which kind of epithelium lines the trachea, bronchi, and bronchioles, and why?

Answer 5

Ciliated columnar epithelium because the cilia help to remove debris and micro-organisms from the airways.

Question 6

Define pseudostratified.

Answer 6

Where a cell appears to be stratified, but each cell is actually in contact with the basement membrane. This means that the cell gives the illusion of having different layers.

Question 7

What kind of cells produce mucus?

Answer 7

Goblet cells.

Question 8

Which features of gas exchange surfaces ensure rapid gas exchange?

Answer 8

• Large surface area of alveoli
• Numerous capillaries around the alveoli
• Thin walls of alveoli and capillaries

Question 9

What is the rate diffusion dependent on?

Answer 9

• Surface area
• Concentration gradient
• Thickness of gas exchange surface

Question 10

What is the general structure of an amino acid?

Answer 10

Question 11

What do two amino acids join to form in a condensation reaction?

Answer 11

A dipeptide.

Question 12

What is a polypeptide?

Answer 12

A long chain of amino acids.

Question 13

What is the primary structure of a protein?

Answer 13

The sequence of amino acids in the polypeptide chain.

Question 14

What are the two secondary structures of proteins?

Answer 14

α-helix and β-pleated sheet.

Question 15

What type of bond stabilises the secondary structures of proteins?

Answer 15

Hydrogen bonds between the C=O of the carboxylic acid and the -NH of the amine group.

Question 16

What is the tertiary structure of a protein?

Answer 16

The three-dimensional structure of a protein. Hydrophilic R groups face outwards, while hydrophobic R groups face the inside of the protein.

Question 17

Define globular proteins.

Answer 17

Proteins where the polypeptide chain is folded into a compact spherical shape. These proteins are soluble as the hydrophilic side chains project from the outside of the molecule. E.g. haemoglobin

Question 18

Define fibrous proteins.

Answer 18

Proteins that remain as long chains. Several polypeptide chains can be cross-linked for additionl strength. E.g. Collagen

Question 19

What is the difference between a lipid and a phospholipid?

Answer 19

Instead of three fatty acids, a phospholipid has two fatty acids and a negatively charged phosphate group which replaces the third fatty acid.

Question 20

What is the general structure of a phospholipid?

Answer 20

Question 21

Describe the structure of a phospholipid bilayer.

Answer 21

When in water, the phosphate heads are attracted to the water because they are polar. Therefore, they face outwards while the fatty acid tails are non-polar and face away from the water.

Question 22

What else composes a cell surface membrane other than just the phospholipid bilayer?

Answer 22

Glycoproteins, glycolipids, proteins, and cholesterol.

Question 23

What are glycoproteins?

Answer 23

Protein molecules with polysaccharides attached.

Question 24

What are glycolipids?

Answer 24

Lipid molecules with polysaccharides attached.

Question 25

What does the fluid mosaic model of the cell surface membrane suggest?

Answer 25

That some proteins within the membrane are not fixed and can move around in the phospholipid bilayer.

Question 26

Which two biochemists proposed the fluid mosaic model?

Answer 26

S. John Singer and Garth Nicholson.

Question 27

How do substances pass through cell membranes?

Answer 27

• Diffusion
• Osmosis
• Active Transport
• Exocytosis
• Endocytosis

Question 28

Define diffusion.

Answer 28

The net movement of molecules or ions from a region of high concentration to an area of low concentration until equilibrium is reached.

Question 29

Which kind of molecules use diffusion to pass through cell membranes?

Answer 29

Small molecules such as oxygen or carbon dioxide.

Question 30

Define facilitated diffusion.

Answer 30

Diffusion that takes place through channel proteins.

Question 31

How do carrier proteins move ions or molecules across the membrane?

Answer 31

• The ion or molecule binds to a specific site on the protein
• The protein changes shape
• The ion or molecule crosses the membrane

Question 32

What does the term passive transport refer to?

Answer 32

Transport that requires no metabolic energy, such as diffusion and facilitated diffusion.

Question 33

Define osmosis.

Answer 33

The net movement of water molecules from a solution with a lower concentration of solute to a solution with a higher concentration of solute through a partially permeable membrane.

Question 34

Define active transport.

Answer 34

When substances are moved across a membrane through carrier proteins against the concentration gradient. Energy is required for this process.

Question 35

Which process provides energy for active transport?

Answer 35

Respiration.

Question 36

Which two processes allow larger molecules to be transported across cell membranes?

Answer 36

Exocytosis and endocytosis.

Question 37

How do endocytosis and exocytosis transport substances through the cell membrane?

Answer 37

Through vesicles, which carry the substance. The vesicles fuse with the cell membrane and carry the substance through the membrane.

Question 38

What happens if there is excess water in the mucus lining the lungs?

Answer 38

• The epithelial cells detect if there is excess water
• Carrier proteins in the basal membranes of epithelial cells pump sodium ions (Na⁺) out of the cells
• The concentration of Na⁺ in the cells falls, creating a concentration gradient
• Sodium ions transport down this concentration gradient into the cell by facilitated diffusion
• The tissue fluid now contains more positive ions than mucus, so negative chloride ions diffuse from the mucus into the tissue fluid
• The raised concentration of sodium and chloride ions in the tissue fluid causes water to draw out of the mucus by osmosis into the cell

Question 39

Why can’t the lungs of a person with CF regulate water levels in the mucus?

Answer 39

The CFTR protein may be faulty or not present.

Question 40

What are the differences between endocrine and exocrine glands?

Answer 40

Endocrine glands secrete directly into the blood, whereas exocrine glands secrete into a duct. Endocrine glands also release hormones.

Question 41

How does the pancreas aid the digestion of food?

Answer 41

Pancreatic cells produce enzymes that help in the breakdown of proteins and are delivered to the gut through the pancreatic duct.

Question 42

How does CF affect the pancreas?

Answer 42

• The pancreatic duct can become blocked with mucus, impairing the release of digestive enzymes
• The trapped enzymes damage the pancreas, forming cysts
• The enzymes can also damage the cells in the pancreas that produce insulin, resulting in a form of diabetes

Question 43

Define enzymes.

Answer 43

Globular proteins that act as biological catalysts.

Question 44

Outline the Lock-and-Key theory.

Answer 44

The theory that enzymes and substrates have a fixed shape and can only form an enzyme-substrate complex with the specific active site.