Yacoubb's Bio 3+4 Questions

[Scooby]

As long as you didn't word your answer in such a way that implied that glucose is the only product, I doubt you'd lose a mark (unless they were looking for you to write maltose as well, which I kinda doubt). 

Oh, and try to avoid definitives wherever possible - there's pretty much always going to be an exception, and depending on how much of a hardass your examiner is you may or may not be marked down for it

[psyxwar]

Glucose and maltose aren't the only possible products for amylases though, so I'm not sure why you'd be more specific for the sake of specificity anyway

[Yacoubb]

Yeah for that answer I would have just stuck with:

Amylase is an enzyme that catalyses the breakdown of starch (its substrate).

[Scooby]

Glucose and maltose aren't the only possible products for amylases though, so I'm not sure why you'd be more specific for the sake of specificity anyway

Well, yeah, but I'm just talking about alpha-amylase here

[Yacoubb]

Can someone help me clarify my understanding of this:

In the blood condition known as Immune Thrombocytopenic Purpura (ITP), the immune system destroys platelets in the blood but does not damage the cells in the bone marrow that manufacture them. Since the blood platelets are always low in number, the cells in the bone marrow of ITP sufferers are continually stimulated in the feedback loop.

ITP is an example of:
(a) an allergic disorder
(b) a hypersensitivity
(c) an immune deficiency
(d) an autoimmune disease



I answered C, but the answer is D. I answered C because it mentions that the cells in the bone marrow that produce the platelets are not damaged. An autoimmune disease is an immune deficiency where the self-non self recognition is deficient and as a result, are attacked and destroyed as an immune defence mechanism.

Can someone please clarify this? Thanks

[swagsxcboi]

Can someone help me clarify my understanding of this:

In the blood condition known as Immune Thrombocytopenic Purpura (ITP), the immune system destroys platelets in the blood but does not damage the cells in the bone marrow that manufacture them. Since the blood platelets are always low in number, the cells in the bone marrow of ITP sufferers are continually stimulated in the feedback loop.

ITP is an example of:
(a) an allergic disorder
(b) a hypersensitivity
(c) an immune deficiency
(d) an autoimmune disease



I answered C, but the answer is D. I answered C because it mentions that the cells in the bone marrow that produce the platelets are not damaged. An autoimmune disease is an immune deficiency where the self-non self recognition is deficient and as a result, are attacked and destroyed as an immune defence mechanism.

Can someone please clarify this? Thanks

Immune deficiency is when the immune system loses ability to fight infectious disease. eg. AIDS
Autoimmune disease is when the immune system identifies self cells as non-self and attacks them. eg. Type 1 Diabetes

[Yacoubb]

Immune deficiency is when the immune system loses ability to fight infectious disease. eg. AIDS
Autoimmune disease is when the immune system identifies self cells as non-self and attacks them. eg. Type 1 Diabetes

Okay then fe

[Yacoubb]

Would the following explanations regarding the levels of molecular organisation of proteins be good?

Primary structure:
Refers to the linear sequence of amino acids of a polypeptide, determined by the coded instructions of DNA.

Secondary structure:
The secondary structure of a protein refers to partial folding of the polypeptide chain as a result of hydrogen bonds forming between H and O atoms in the backbone of the polypeptide, causing the polypeptide folding upon itself.

-Alpha Helix:
Results when tight polypeptide coils are held together by hydrogen bonds at every fourth amino acid.

-Beta-pleated sheet:
Results when regions of a polypeptide chain life parallel to each other, and hydrogen bonds form between parallel parts of the backbone of the polypeptide chain to hold the structure together.

Random coil:
Refers to hydrogen bonds forming as a result of H and O interactions in the backbone of the polypeptide, and folding to form a coiled shape not common to an alpha-helix or beta-pleated sheet.

Tertiary Structure:
Refers to the overall, three-dimensional structure of a protein as a result of the complex molecular shape forming (conformation). The tertiary structure of a protein is formed as a result of interactions between the side chains of a polypeptide. The tertiary structure of a protein is critical to the biological function of the protein.

Quaternary Structure:
Refers to a protein made up of two or more polypeptide chains. The quaternary structure results from the combined overall shape of all linked polypeptide chains.

[psyxwar]

Would the following explanations regarding the levels of molecular organisation of proteins be good?

Primary structure:
Refers to the linear sequence of amino acids of a polypeptide, determined by the coded instructions of DNA.

Secondary structure:
The secondary structure of a protein refers to partial folding of the polypeptide chain as a result of hydrogen bonds forming between H and O atoms in the backbone of the polypeptide, causing the polypeptide folding upon itself.

-Alpha Helix:
Results when tight polypeptide coils are held together by hydrogen bonds at every fourth amino acid.

-Beta-pleated sheet:
Results when regions of a polypeptide chain life parallel to each other, and hydrogen bonds form between parallel parts of the backbone of the polypeptide chain to hold the structure together.

Random coil:
Refers to hydrogen bonds forming as a result of H and O interactions in the backbone of the polypeptide, and folding to form a coiled shape not common to an alpha-helix or beta-pleated sheet.

Tertiary Structure:
Refers to the overall, three-dimensional structure of a protein as a result of the complex molecular shape forming (conformation). The tertiary structure of a protein is formed as a result of interactions between the side chains of a polypeptide. The tertiary structure of a protein is critical to the biological function of the protein.

Quaternary Structure:
Refers to a protein made up of two or more polypeptide chains. The quaternary structure results from the combined overall shape of all linked polypeptide chains.

Yup. You don't need that much detail for any of the sub-secondary structures.

[Yacoubb]

Can someone check if my knowledge of allergies is accurate:

* The immune system comes into contact with an allergen; plasma cells secrete IgE antibodies with antigen-binding sites complementary to the shape of the antigens of the allergen.
* Some of these IgE antibodies bind to the surface of mast cells.
* On a subsequent occasion, when the allergen binds to the IgE antibodies on the surface of mast cells, degranulation of histamine occurs and the release of histamine results in difficulty breathing and other signs and symptoms common to allergies.

Something to add or take off? Thanks!

Do we need to know that a person is sensitised to a particular allergen when immature B-lymphocytes come into contact with the antigens of the allergen?

[Yacoubb]

Are these good ways of describing the effects of temperatures on enzymes?

At temperatures below the optimum temperature of an enzyme, enzymatic activity is reduced due to less kinetic energy being present, and thus, reduced molecular movement. Hence, there are fewer collisions between enzymes and their substrate molecules, resulting in the decrease of the enzyme's activity rate.

At temperatures above the optimum temperature of an enzyme, the enzyme begins to denature. The active site configuration is permanently altered as a result of disruptions in the bonds forming the active site, preventing the substrate molecules from being able to attach to the enzyme, and thereby decreasing the enzyme's activity rate.

Could someone just add/remove/change anything that needs ammendments ?

[vox nihili]

Are these good ways of describing the effects of temperatures on enzymes?

At temperatures below the optimum temperature of an enzyme, enzymatic activity is reduced due to less kinetic energy being present, and thus, reduced molecular movement. Hence, there are fewer collisions between enzymes and their substrate molecules, resulting in the decrease of the enzyme's activity rate.

At temperatures above the optimum temperature of an enzyme, the enzyme begins to denature. The active site configuration is permanently altered as a result of disruptions in the bonds forming the active site, preventing the substrate molecules from being able to attach to the enzyme, and thereby decreasing the enzyme's activity rate.

Could someone just add/remove/change anything that needs ammendments ?

The big issue with these are that they describe enzyme action in terms of chemistry, so you may find that this is beyond the Biology course. In my understanding though, the first is correct, the second is not strictly true.

The reason enzymes do not function as well above optimum temperature is not necessarily related to the denaturation of the enzyme. An enzyme in a human, for example, is not denatured at 38°C for examples, nor is it beginning too. The reason it won't function as well is because the interaction (binding) between the enzyme and its substrate isn't as stable at higher temperatures, probably because higher temperatures deliver enough energy to break that bond.

[Yacoubb]

The big issue with these are that they describe enzyme action in terms of chemistry, so you may find that this is beyond the Biology course. In my understanding though, the first is correct, the second is not strictly true.

The reason enzymes do not function as well above optimum temperature is not necessarily related to the denaturation of the enzyme. An enzyme in a human, for example, is not denatured at 38°C for examples, nor is it beginning too. The reason it won't function as well is because the interaction (binding) between the enzyme and its substrate isn't as stable at higher temperatures, probably because higher temperatures deliver enough energy to break that bond.

I guess it would depend upon the context of the question and the specification regarding the temperature (and then determining how much higher it is than the optimum temperature of the enzyme). So to be on the safe side, should I just reference the disruptions in bonds holding together the active site subsequently altering the configuration of the active site as a result of heating an enzyme above its temperature optima?

Thanks for your help.

[Yacoubb]

Could someone check whether my descriptions for each stage of photosynthesis are accurate?

Light-dependent stage:
- In the grana of the chloroplast, light energy is absorbed by chlorophyll molecules.
- Water is split to form H+ ions and oxygen gas.
- ATP is formed from ADP + Pi (i.e. the phosphorylation of ADP)
- NADPH is formed.

Light-independent stage:
- In the stroma of chloroplasts, the Calvin Cycle occurs.
- In the Calvin Cycle, carbon dioxide reacts with H+ (provided by NADPH) to synthesize glucose.
- ATP provides the energy to synthesise the glucose.

I'm trying not to deviate too much from the study design and so that's why I'm trying to simplify it without explaining things like the carbon fixation, etc.

[psyxwar]

^you should know that electron transport occurs in light dependent stage. VCAA had a multiple choice question where that knowledge was necessary.

Hence, for light dependent:

-Chlorophyll in grana absorb light energy, exciting their electrons which enter an electron transport chain
-Water is split to replenish chlorophyll's lost electrons, producing H+ and molecular oxygen
-As a product of electron transport, ATP and NADPH are formed, which go to the light independent stage