A level Biology: Post your doubts here!

[princess Anu]

and small lumen of arteries is to maintain blood pressure right?

 

[princess Anu]

somebody explain why is the option B not correct ?View attachment 52925

is the ans A?

 

[MYLORD]

is the ans A?

no it is D

 

[MYLORD]

is the ans A?

i really didn't get the question , did u ?

 

[princess Anu]

are you sure :O D doesn't make sense at all

i really didn't get the question , did u ?

 

[alexkay]

can anyone predict the experiment for paper 5 on 8th may?

 

[qwertypoiu]

can anyone predict the experiment for paper 5 on 8th may?

Oh yeah it will definitely be gene technology...

 

[MYLORD]

are you sure :O D doesn't make sense at all

i know ,it doesnt make any sense thats why i asked the question in the first place

 

[MYLORD]

Oh yeah it will definitely be gene technology...

can u help me understand this question ?
i chose B but the answer is D

 

[qwertypoiu]

can u help me understand this question ?
i chose B but the answer is D
View attachment 52936

I believe this has to do with definition of net primary productivity as well as gross primary productivity.
Since these are not in our syllabus, I wouldn't worry too much about it.

 

[Studydayandnight]

Guys! Explain this one please!

Correct answer is D.

 

[Studydayandnight]

This one as well! Correct answer is D.

 

[qwertypoiu]

Guys! Explain this one please!

Correct answer is D.

When oxygen diffuses from the lung to the blood it passes through 5 membranes.

Once oxygen enters the air space inside alveolus, it:

• Enters into squamous epithelium of alveolus.
• Exits from the squamous epithelium of alveolus.
• Enters into endothelial cells of capillaries.
• Exits endothelial cell of capillary, to enter the lumen of capillary. (here is blood plasma)
• Enter the red blood cell, to bind with one of the 200,000,000 haemoglobin molecules inside.

So that's five for oxygen. It is similar for carbon dioxide, except that it may travel by three modes. Some of it travels by actually binding with haemoglobin amine terminal (10%), others simply dissolve in blood plasma (5%), and most of them as HCO3- ions, dissolved in blood plasma (85%).
So depending on which situation arises, a CO2 molecule may or may not have to enter the red blood cell.
Therefore, for CO2, we say it may travel through 4 or 5 membranes.

 

[qwertypoiu]

This one as well! Correct answer is D.

For this question you simply have to identify energy that was converted into chemical energy in the form of glucose from the plant photosynthesising. All energy in glucose came from the sun originally after all.
So, the first three all do not fit into this category, because they remain as light or heat energy, and so were never used for photosynthesis.

Used for growth: yes, this fits, because for growth the energy first was turned into chemical energy in the form of glucose, then this glucose was used as an energy source. (perhaps first ATP was made before energy was used)

Used for other life processes: yep. Because all life processes that require energy happen in cells, and the source of this energy is always glucose.

Respiratory heat losses: one might think that this energy did not undergo photosynthesis, but you have to be careful! For a plant to lose energy through heat losses, it must have gained chemical energy, done respiration using this chemical energy, then lost some of THIS energy in heat. So this counts as well.

In other words we just look for energy that entered the plant and stayed, because the only way to stay as energy inside the plant is as chemical energy, by undergoing photosynthesis.

Adding those three energy quantities should get you D.

 

[bubbles1997]

Please share the guess paper for biology practical 33
https://www.xtremepapers.com/community/threads/as-biology-33-2015-m-j.41027/

 

[Jeezan]

Which type of cell will contain the highest proportion of single membrane bound structures ?
A - ciliated epithelial cell
B- goblet cell
C- RBC
D-smooth muscle cell

The answer is B
May i know the reason ?

 

[qwertypoiu]

Which type of cell will contain the highest proportion of single membrane bound structures ?
A - ciliated epithelial cell
B- goblet cell
C- RBC
D-smooth muscle cell

The answer is B
May i know the reason ?

Goblet cells produce a lot of mucus.
Mucus has glycoproteins in it, so to produce glycoprotein, the goblet cell needs endoplasmic reticulum.
To secrete the mucus produced, Golgi vesicles are involved to perform exocytosis.
ER, and Golgi apparatus are both single membrane bound structures, and is found in high proportion in goblet cells.

 

[Jeezan]

Goblet cells produce a lot of mucus.
Mucus has glycoproteins in it, so to produce glycoprotein, the goblet cell needs endoplasmic reticulum.
To secrete the mucus produced, Golgi vesicles are involved to perform exocytosis.
ER, and Golgi apparatus are both single membrane bound structures, and is found in high proportion in goblet cells.

Thank you

 

[Jeezan]

http://theallpapers.com/papers/CIE/AS_and_ALevel/Biology (9700)/9700_s11_qp_11.pdf
q.14
why cant the answer be A ?

 

[Awesome12]

http://theallpapers.com/papers/CIE/AS_and_ALevel/Biology (9700)/9700_s11_qp_11.pdf
q.14
why cant the answer be A ?

They have aforementioned that the inhibitors bind to the enzyme substrate complex. Such complexes are found only at the active site. Thus the inhibitor is a competitive inhibitor, and you can negate 2.