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Week One Review notes Flashcards

1
Q

Q: What are the two main parts of a phospholipid?

A

A: A hydrophilic phosphate head and two hydrophobic fatty acid tails.

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2
Q

Q: Why do phospholipids form a bilayer in water?

A

A: Because the hydrophobic tails avoid water, while the hydrophilic heads interact with it.

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3
Q

Q: What does the term “fluid mosaic model” refer to?

A

A: A dynamic membrane structure where proteins float in or on a fluid bilayer of phospholipids.

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4
Q

Q: What allows the membrane to be flexible and self-repairing?

A

A: The fluidity of the phospholipid bilayer due to weak hydrophobic interactions.

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5
Q

Name three types of membrane proteins based on function.

A

A: Transport, receptor, enzymatic, recognition, adhesion, and attachment proteins.

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6
Q

Q: What is the function of glycoproteins in membranes?

A

A: Cell-cell recognition and signaling.

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7
Q

Q: Which membrane protein is used in facilitated diffusion of glucose?

A

A: Glucose transporter (a carrier protein).

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8
Q

Q: Is cholesterol found in both animal and plant cell membranes?

A

A: No, only in animal cell membranes.

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9
Q

Q: What are the three key roles of cholesterol in membranes?

A

A: Reduces fluidity, maintains membrane integrity, and decreases permeability.

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10
Q

Q: How does cholesterol affect membrane fluidity at low temperatures?

A

A: It prevents solidification by disrupting phospholipid packing.

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11
Q

Q: What is the main difference between simple and facilitated diffusion?

A

A: Simple diffusion doesn’t need proteins; facilitated diffusion uses channels or carriers.

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12
Q

Q: What kind of molecules move via simple diffusion?

A

A: Small, non-polar molecules like O₂ and CO₂.

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13
Q

Q: Define osmosis.

A

A: The passive movement of water across a semi-permeable membrane from low solute to high solute concentration.

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14
Q

Q: What is endocytosis?

A

A: The process by which cells engulf materials by forming a vesicle from the plasma membrane.

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15
Q

Q: What is exocytosis used for?

A

A: Releasing substances like hormones or neurotransmitters from the cell.

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16
Q

Q: Why are isotonic solutions used in IV drips?

A

A: To prevent cells from gaining or losing water, avoiding bursting or shriveling.

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17
Q

Q: What is the most commonly used isotonic solution in hospitals?

A

A: 0.9% NaCl (normal saline).

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18
Q

Q: What happens if a cell is placed in a hypertonic solution?

A

A: It loses water and shrinks (crenation).

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19
Q

Describe how secretory proteins found in structure X are produced and transported within the cell.

A

-secretory proteins are produced by the ribosomes, which occurs on the rough endoplasmic reticulum
- proteins are folded and modified inside the rough endoplasmic reticulum
- vesicles are formed to transport proteins from rough endoplasmic reticulum
- vesicles are transported to the Golgi apparatus
- where proteins are modified and repackaged in secretory vesicles before reaching the plasma membrane

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20
Q

Processes that occur by osmosis

A

1) reuptake of water by cells in the wall of the intestine
2) loss of water from a plant cell in a hypertonic environment

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21
Q

Benefits of compartmentalisation:

A

1) allows organells to have specialized functions
2) allows metabolic processes to be isolated from each other
3) Prevents incompatible reactions from occurring in the same part of cell

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22
Q

Muscle levels of organisation (largest to smallest)

A

1) Muscle
2) Muscle bundle
3) Muscle fiber
4) Myofybril
5) Sarcomere

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23
Q

A- band

A

length of thick filaments (myosin), stays the same during contraction

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24
Q

I-band

A

Only thin filaments (actin) shortens during contraction

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25
Actin (thin filament)
has binding sites for myosin heads - covered by tropomyosin and troponin at rest
26
Myosin (thick filament)
Has a golf-club shaped head that attach to actin - Uses ATP to move and pull actin
27
Muscle contraction (sliding filament theory)
1) Acetylcholine is released --> triggers action potential 2) calcim released from sarcoplasmic reticulum bind to troponin 3) Myosin head bind to action, forming cross bridges 4) Power stroke - pulls actin toward the m-line, shortens sarcomere --> contraction occurs 5) ATP binds to myosin head leading to ATP hydrolysis
28
Role of calcium
Binds to troponin, which causes tropomyosin to expose binding sites on actin
29
Role of ATP
1) Detaches myosin from actin 2) Recocks myosin head after power stroke 3) Powers calcium reuptake into SR for relaxation
30
Name two proteins involved in regulating the binding of actin and myosin in a relaxed muscle.
1) tropomyosin 2) troponin
31
Which muscle types are involuntary
Cardiac, Smooth
32
Explain the role of ATP in muscle contraction at the molecular level.
- ATP binds to myosin heads, causing them to detach from actin after a power stroke. - ATP is then hydrolyzed to ADP and Pi, providing energy for the myosin heads to reset and reattach to actin, allowing continued contraction.
33
What are antagonistic muscles and give an example.
- they move in opposite directions or work in pairs - has to be around the SAME joint Ex. Biceps / triceps
34
how many mm equal 1 micrometer
1,000 mm
35
Q: What is the function of amylase and where is it produced?
A: Breaks down starch into maltose; produced by salivary glands and pancreas.
36
Q: What prevents backflow from the ventricles to the atria?
A: Atrioventricular (AV) valves – tricuspid and bicuspid/mitral valves.
37
Q: What is the function of the pulmonary artery?
A: Carries deoxygenated blood from the heart to the lungs.
38
Q: What is double circulation?
A: Blood passes through the heart twice per full circuit: pulmonary and systemic circulation.
39
Q: What happens during atrial systole?
A: Atria contract and push blood into the ventricles.
40
Q: What valves are open during ventricular systole?
A: Semilunar valves (pulmonary and aortic).
41
Q: What causes the “lub” heart sound?
A: Closure of AV valves at the beginning of ventricular systole.
42
Q: Why is there a delay at the AV node?
A: To allow the atria to finish contracting before the ventricles start.
43
Q: Which direction does oxygen diffuse during gas exchange?
A: From alveoli → capillaries.
44
Q: What makes alveoli efficient for gas exchange?
A: Thin walls, moist surface, large surface area, and dense capillary network.
45
Q: What is atherosclerosis and how is it linked to smoking?
A: Build-up of plaque in arteries; smoking contributes to arterial damage and cholesterol deposits.
46
Name the two circuits of the heart and describe their function.
1) Pulmonary circulation: carries deoxygenated blood from the right ventricle to the lungs and returns oxygenated blood to the left atrium. 2) Systemic circulation: carries oxygenated blood from the left ventricle to the body and returns deoxygenated blood to the right atrium.
47
Sequence of electrical impulses controlling the heartbeat
- Impulse originates in the sinoatrial (SA) node. - SA node causes atria to contract. - Impulse passes to the atrioventricular (AV) node. - Then sent down the bundle of His and Purkinje fibers. - Causes ventricles to contract from the apex upwards. (1)
48
Describe the process of inhalation.
- Diaphragm contracts and flattens. - External intercostal muscles contract, lifting the rib cage. - Volume of the thoracic cavity increases. - Pressure inside lungs decreases, drawing air in.
49
Explain how the structure of the alveoli is adapted to facilitate efficient gas exchange.
- Large surface area due to spherical shape and numerous alveoli. - Thin walls (one cell thick) for short diffusion distance. - Surrounded by dense capillary network. - Moist surface to allow gases to dissolve. - Surfactant reduces surface tension and prevents alveoli collapse.
50
State the role of hemoglobin in the transport of oxygen and carbon dioxide in the blood.
- Hemoglobin binds oxygen in red blood cells to form oxyhemoglobin. (1) - Releases oxygen in tissues where oxygen pressure is lower. (1) - Carries some carbon dioxide as carbaminohemoglobin or via conversion to bicarbonate ions. (1)
51
What is the Bohr shift (Bohr effect) in respiration?
The Bohr shift is a phenomenon where hemoglobin releases oxygen more readily in environments with high carbon dioxide (CO₂) levels or low pH (acidic conditions). This happens in actively respiring tissues, where CO₂ production is high, lowering the pH. The change in pH alters hemoglobin’s shape, reducing its affinity for oxygen and promoting oxygen release. EASIER EXPLANATION The Bohr shift means that hemoglobin lets go of oxygen more easily when there is a lot of carbon dioxide or when the environment is more acidic (low pH). This helps active tissues (like muscles during exercise) get more oxygen when they need it most.
52
What is cooperative binding in hemoglobin?
Cooperative binding means that when one oxygen molecule binds to hemoglobin, it makes it easier for the next oxygen molecules to bind. 💥 This allows hemoglobin to pick up lots of oxygen in the lungs quickly and release it in tissues when needed.
53
What do baroreceptors do?
Baroreceptors are pressure sensors found in the walls of blood vessels (like the aorta and carotid arteries). They detect changes in blood pressure and send signals to the brain (medulla) to help maintain stable blood pressure. 🩺 If pressure is too high, heart rate is reduced. 🩸 If pressure is too low, heart rate increases.
54
What do chemoreceptors do?
Chemoreceptors detect changes in blood chemistry, especially carbon dioxide, oxygen, and pH. Found in places like the carotid artery and aorta, they send messages to the brain to adjust breathing and heart rate. 💨 If CO₂ is high or pH drops (acidic), breathing and heart rate increase to fix it.
55
What happens during ultrafiltration in the kidney?
High pressure in the glomerulus forces water, urea, glucose, and ions into Bowman’s capsule. Blood cells and proteins stay in the capillaries because they’re too big to pass through.
56
What is selective reabsorption and where does it occur?
It occurs in the proximal convoluted tubule (PCT). Useful substances like glucose, amino acids, and water are actively reabsorbed back into the blood.
57
How is the PCT adapted for selective reabsorption?
It has microvilli for a large surface area and lots of mitochondria to provide energy for active transport.
58
What is osmoregulation?
The control of water and solute balance in the body to maintain homeostasis.
59
How do freshwater animals regulate water?
They constantly gain water and lose salts, so they excrete lots of dilute urine and actively take in salts through their gills.
60
How do saltwater animals regulate water?
They risk dehydration, so they drink seawater, excrete salt through gills, and produce small amounts of concentrated urine.
61
What does ADH do in the body?
ADH makes the collecting ducts in the kidney more permeable to water, so more water is reabsorbed and urine becomes more concentrated.
62
When is ADH released and what triggers it?
ADH is released when blood is too concentrated (low water levels). This helps retain water and reduce water loss in urine.
63
What is dialysis and when is it used?
Dialysis is a treatment for kidney failure. It filters waste, extra water, and salts from the blood using a machine with a semi-permeable membrane.
64
The benefits of using glycogen as a short-term energy storage molecule are…
Any two of the following: Glycogen can be built up and broken down rapidly whereas fat metabolism takes longer; [1 mark] Glycogen can fuel anaerobic respiration (for short-term energy requirements) whereas fats predominantly provide fuel for aerobic respiration; [1 mark] Glycogen is stored directly in the cells where it may be required eg. muscle cells whereas fats are stored in adipose tissue; [1 mark] [Total: 2 marks]
65
The positive feedback loop during birth involves…
Oxytocin stimulates contractions of the (muscles in the) uterus walls; [1 mark] Stretch receptors detect the contractions and signal to the pituitary gland; [1 mark] The pituitary gland releases more oxytocin (stimulating more contractions, and so on...); [1 mark]
66
Formula for percent decrease
Change / starting point x100

Biology Revision (12 decks)

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