Week 1 formative quiz questions

Question 1

What is plasma pH proportional to?

hint: think bicarbonate and carbonic acid conc.

Answer 1

Plasma pH is proportional to bicarbonate ion conc. divided by carbonic acid conc. (or CO2 levels as you can substitute CO2 for carbonic acid and get the same effect in terms of movement of pH

Question 2

Are all pathological process naturally occuring?

Answer 2

No, as pathological processes can occur unnaturally, for example following traumatic injury or iatogenic (caused by healthcare) harm

Question 3

Ribosomes are involved in what process?

Answer 3

Protein synthesis

Question 4

What % of the human body is water?

Answer 4

60%

Question 5

Is the entry of sodium ions to a nerve cell during an action potential positive or negative feedback? Why?

Answer 5

This is a good example of positive feedback as when a nerve cell is stimulated the cell membrane becomes permeable to sodium. Entry of sodium to the nerve cell causes the nerve cell membrane to become even more permeable to sodium thus more sodium enters and so on. This “chain reaction” is termed positive feedback

Question 6

Will a SATURATED fatty acid have the maximum or minimum number of double bonds?

Answer 6

Minimum, A saturated fatty acid has no double bonds.

Question 7

Amphipathic molecules have what two parts?

Answer 7

Water loving (hydrophilic) and water repellent (hydrophobic)

Question 8

does more double bonds present in the fatty acids of a cell membrane make the membrane more or less flexible?

Answer 8

Double bonds increase the flexibility of a fatty acid chain

Question 9

True or false: plasma makes up less than a third of extracellular volume?

Answer 9

True. Plasma accounts for about 3L of the 14L that is extracellular fluid (11L is interstitial fluid)

Question 10

True or false: When you eat a sugary donut, merely the presence of food in your stomach stimulates the release of insulin from the pancreas prior to the glucose being absorbed across the gut wall. This is an example of negative feedback

Answer 10

False. This is instead an example of a feedforward mechanism. Blood glucose conc. has not yet increased but the body pre-empts an increase due to the presence of food in the stomach and promotes the release of insulin to minimise the disturbance to blood glucose levels when the glucose is absorbed

Question 11

True or false: A rise in buffer concentration will result in a fall in pH

Answer 11

False. A rise in buffer conc. will increase pH. Remember the henderson hasselbalch equation which describes the relationship between buffer and pH. Simply put pH is proportional to buffer conc. divided by protonated buffer concentration so as buffer conc. goes up, pH goes up and vice versa

Question 12

True or false: intracellular fluid volume can be measured directly

Answer 12

False. We can only directly measure the volume of fluid compartments of which plasma is a component because we only have access to the plasma (via veins) to inject the marker and sample the diluter marker after equilibration. Plasma is not a component of ICF. However ICF is a component of TBW, so if we measure TBW using heavy water and measure ECF using radiolabelled Na (remember plasma is a component of both ECF and TBW) we can calculate ICF indirectly by subtracting ECF from TBW

Question 13

True or false: Phosphate ions are the main buffering agents in plasma

Answer 13

False. Bicarbonate ions are the main buffering agents in plasma. Phosphate ions buffer intracellular fluid

Question 14

True or false: The nucleic acid base adenine is only found in DNA

Answer 14

False. Adenine is found in both DNA and RNA. All base pairs except Thymine are found in DNA and RNA. The RNA base pair for adenine is uracil

Question 15

True or false: Bicarbonate and phosphate ions are the major buffer systems in the body

Answer 15

True. Theses two ions form the main buffering agents that help maintain body fluid pH at 7.4

Question 16

True or false: The GMC develops postgraduate training programmes and exams

Answer 16

False. The royal colleges do this, and they are approved by the GMC. The GMC is the regulatory body for medicine in the UK

Question 17

True or false: Having a drink of water when you are thirsty is an example of a feedforward mechanism

Answer 17

False. This is instead an example of negative feedback. Your homeostasis of water is already disturbed causing you to feel thirsty and seek water. By drinking water you remove the trigger that caused the thirst, thus removing the thirst response = negative feedback

Question 18

True or false: Radiolabelled albumin can be used to measure ECF volume

Answer 18

False. Albumin is a plasma protein and thus is confined to the plasma compartment

Question 19

True or false: Ions can move freely between plasma and interstitial fluid

Answer 19

True. Ions can cross the capillary wall easily

Question 20

True or false: ISF volume can only be measured indirectly by measuring ECF volume and plasma volume and subtracting the latter from the former i.e. ECF - plasma = ISF

Answer 20

True. We can only directly measure the volume of fluid compartments of which plasma is a component because we only have access to the plasma (via veins) to inject the marker and sample the diluter marker after equilibration. Plasma is a component of ECF but not ISF

Question 21

True or false: 150mg of radio labelled albumin, injected into the plasma of a 70kg adult male is likely to produce a sample conc. of 0.05mg/ml after equilibration assuming none is metabolised

Answer 21

TRUE. this would indicate plasma vol = 3L, which is what we would expect in a 70kg adult male (150/3000ml = 0.05mg/ml) Remember albumin is restricted to the plasma and we know plasma volume is around 3L in an adult male, so if you divide 150mg by 3000ml you get 0.05mg/ml

Question 22

True or false: Chylomicrons are important structure for carrying protein around the blood

Answer 22

FALSE. Chylomicrons ar important structure for carrying LIPID around the blood. Proteins are generally water soluble so are readily transported in plasma. Lipids are not water soluble and thus need to be packaged into chylomicrons to ease transport in the blood

Question 23

True or false: The conversion of NAD+ to NADH is an example of oxidation

Answer 23

FALSE. It is an example of reduction. NAD+ gains an electron to become NADH (remember OIL RIG where reduction is gain (of elections)). However NAD+ is an oxidising agent in that it is itself reduced to NADH

Question 24

True or false: Multipotent stem cells can differentiate into any cell type in the body

Answer 24

False. Multipotent stem cells can differentiate in many, but not all cell types. Pluripotent stem cells can form any cell in the body. Adult stem cells are multipotent. Embryonic stem cells are pluripotent

Question 25

True or false: The role of the Golgi apparatus is to synthesise new protein

Answer 25

False. The Golgi apparatus packages up protein in preparation for transport out of the cell. It is the job of the ribosomes to synthesise new protein.

Question 26

True or false: Mitochondria are the primary site of cellular respiration

Answer 26

True - they are

Question 27

True or false: Hydrophilic molecules are water soluble

Answer 27

True. The term hydrophilic means ‘water loving’ - they can dissolve readily in water by forming hydrogen bonds. Such substances travel easily in blood

Question 28

True or false:In RNA adenine always pairs with thymine

Answer 28

False - in DNA adenine pairs with thymine, but in RNA adenine pairs with uracil. There is no thymine in RNA, it is replaced with uracil.

Question 29

True or false: The rough endoplasmic reticulum modifies protein after it has been synthesised.

Answer 29

True - The rough endoplasmic reticulum modifies protein after it has been synthesised

Question 30

True or false: 42mg of heavy water, injected into the plasma of a 70kg adult male is likely to produce a sample concentration of 0.01mg/ml after equilibration, assuming none is metabolised or excreted.

Answer 30

False - you would get a sample concentration nearer 0.001mg/ml. A sample concentration of 0.01mg/ml would indicate total body water was around 4,200ml or 4.2L but it is in fact 10 times that at 42L or 42,000ml. Remember water, heavy or otherwise, has access all areas so your sample reflects distribution across all water compartments in the body. If you divide 42mg by 42,000ml you get 0.001mg/ml (not 0.01mg/ml)

Question 31

True or false - we have approx twice as much ECF as we have ICF

Answer 31

FALSE. we have twice as much ICF as we have ECF (ICF is the biggest water compartment in the body, approx 28L ICF compared to 14L ECF)

Question 32

True or false - The term necrosis describes programmed cell death, a part of the normal cell cycle

Answer 32

False - apoptosis is the term that describes programmed cell death. Necrosis describes cell death as a result of injury or infection. It is not part of the normal cell cycle

Question 33

True or false - In a structured patient history, “ICE” stands for “Introduction, Consent and Explanation

Answer 33

False - The acronym “ICE” is commonly used to mean “Ideas, Concerns and Expectations”, and is a helpful summary of what you should cover when gathering information about your patient’s perspective

Question 34

True or false - Body water content, as a proportion of total mass, is decreased in obesity

Answer 34

TRUE - Since fat has the lowest water content of any tissue (muscle has the highest).

Question 35

True or false: The aetiology of a disease is the process by which it develops

Answer 35

FALSE - The aetiology of a disease describes its causative factors. The process by which a disease develops is the pathogenesis

Question 36

True or false: The nucleic acid base uracil is only found in RNA

Answer 36

True: uracil is only found in RNA, and not in DNA

Question 37

True or false: Membrane channels are composed primarily of carbohydrate

Answer 37

False: Membrane channels are composed of protein which is encoded by the cells DNA

Question 38

True or false: Uncharged molecules are generally water soluble

Answer 38

False: uncharged molecules are generally hydrophobic (water hating) and do not dissolve readily in water. Lipids are uncharged molecules – think what happens when you drop oil into water. The fat molecules cluster together to minimise their contact with the aqueous environment.

Question 39

True or false: The amphipathic nature of proteins increases their water solubility

Answer 39

True – most proteins are amphipathic meaning they have a water loving (hydrophilic) and a water repellent (hydrophobic) part. By orientating themselves such that the hydrophobic part gets buried deep within the protein molecule and the hydrophilic part is on the outside exposed to the aqueous environment, the molecule becomes water soluble.

Question 40

True or false: Prokaryote cells have no nucleus

Answer 40

True - Eukaryotic cells have a nucleus, but prokaryotic cells (bacteria) do not

Question 41

True or false: The breakdown of a disaccharide to a monosaccharide occurs via a reaction that consumes water and is known as hydrolysis

Answer 41

True - a reaction that consumes water is hydrolysis

Question 42

True or false: Condensation describes biochemical reactions where two smaller molecules join to form one larger molecule and water is released

Answer 42

True: this describes a condensation reaction

Question 43

True or false: Phosphate ions are the main buffering agents in plasma

Answer 43

False: bicarbonate ions are the main buffering agents in plasma. Phosphate ions buffer ICF

Question 44

True or false: The term homeostasis describes the concept of maintaining static conditions in the internal environment

Answer 44

False - the term homeostasis describes the concept of maintaining similar but not static internal body conditions. Most homeostatically controlled parameters have a normal range within which fluctuation is permitted. When that parameter moves out of the normal range homeostatic mechanisms intervene in an attempt to prevent that disturbance