A level Biology: Post your doubts here!

[Farhad221]

The SI unit for time is Seconds, so while recording results our results should always be in seconds thus it cant be for A and B
and for precise results u always right ur answer to the nearest second (p3 tip) so it cant be D
thus we r left with C

it is C

 

[Farhad221]

yes

Paper2 done?

 

[Lola_sweet]

it is C

I keep forgetting to tell the right answer

 

[Farhad221]

its fine at least u are explaining it to me THAT MATTERS.

I keep forgetting to tell the right answer

 

[Farhad221]

Can you help me with this question?

I keep forgetting to tell the right answer

 

[Farhad221]

I keep forgetting to tell the right answer

I have a question, I know using a calibrated eye piece graticule has no parallex error but does a stage micrometer have one?

 

[Farhad221]

q 3 answer is B

 

[Farhad221]

 

[Farhad221]

Q 12 answer is A
View attachment 52847

 

[Farhad221]

Q 19 answer is C

 

[qwertypoiu]

View attachment 52846 View attachment 52846

1. This is a vacuole. Plants cells have vacuoles, and animal cells don't
At this point, the only possible option is B. Therefore I'd just choose B and continue with other questions. But just for benefit:

2. This is a lysosome.
3. Mitochondria
4. Endoplasmic Reticulum
5. Ribosomes

3,4,5 all exist in both animal and plant cells.
As for lysosomes this is debatable, it depends on your definition for lysosomes. If you're interested have a look here

 

[My Name]

View attachment 52846 View attachment 52846

1-surrounded by a single membrane and enclosing a large fluid-filled space = Vacuole
2-surrounded by a single membrane and enclosing inactivated enzymes= Lysosome (I'm not sure about this one)
3-formed by two membranes enclosing a matrix, the inner membrane is folded= Mitochondria
4-formed by a membrane that has flattened sacs and tubular structures inter-connected throughout the cell= Endoplasmic reticulum
5-formed of nucleic acid and protein attached to membranes or free in the cytoplasm= Nucleus

So that's why the answer would be B

 

[My Name]

1. This is a vacuole. Plants cells have vacuoles, and animal cells don't
At this point, the only possible option is B. Therefore I'd just choose B and continue with other questions. But just for benefit:

2. This is a lysosome.
3. Mitochondria
4. Endoplasmic Reticulum
5. Ribosomes

3,4,5 all exist in both animal and plant cells.
As for lysosomes this is debatable, it depends on your definition for lysosomes. If you're interested have a look here

You posted JUST when I posted!

 

[My Name]

1. This is a vacuole. Plants cells have vacuoles, and animal cells don't
At this point, the only possible option is B. Therefore I'd just choose B and continue with other questions. But just for benefit:

2. This is a lysosome.
3. Mitochondria
4. Endoplasmic Reticulum
5. Ribosomes

3,4,5 all exist in both animal and plant cells.
As for lysosomes this is debatable, it depends on your definition for lysosomes. If you're interested have a look here

Why can't 5 be Nucleus?

 

[princess Anu]

Q 19 answer is C
View attachment 52848

chromosomes appear as two chromatids only during prophase & metaphase
thus you can calculate like : 16+73/ 73+16+11+14+866 * 100 and you'll get 9.08 % so C!

 

[qwertypoiu]

Q 19 answer is C
View attachment 52848

We want chromosomes that appear as two chromatids:
Interphase - nope, DNA appears as loose chromatin form, not chromosomes nor chromatids
Prophase - yes! The DNA material has condensed to appear as two chromatids on every chromosome
Metaphase - yes! At Metaphase the chromosomes just moved towards the equator of the cell, but they all still appear with two chromatids
Anaphase - nope. The chromosomes have been split by centrioles through their microtubule spindle fibers. They do not appear with two chromatids, rather each chromosome has one chromatid only.
Telophase - nope. They have reached the ends and nuclear envelope is forming, but each chromosome has still one chromatid.

Figure the math part out yourself if you can't I'll do it insha Allah

 

[princess Anu]

Somebody help

Q1. Roles of No3- and Mg+2 in plants
Q2. Explain the translocation of sucrose using the mass flow hypothesis

 

[My Name]

Somebody help

Q1. Roles of No3- and Mg+2 in plants
Q2. Explain the translocation of sucrose using the mass flow hypothesis

Answer for 1:
Nitrates- They help in building proteins (amino acids) which are needed for growth.
Magnesium ions- It's the magnesium that makes chlorophyll green. SO they are necessary for Photosynthesis.

If any of these are less the plant will look yellow.

 

[qwertypoiu]

Why can't 5 be Nucleus?

Formed of nucleic acid and protein, attached to membranes or free in the cytoplasm.

This description seems to match that of ribosomes. They are made of ribosomal RNA (rRNA) and protein and contain a small and a large subunit.

 

[qwertypoiu]

Somebody help

Q1. Roles of No3- and Mg+2 in plants
Q2. Explain the translocation of sucrose using the mass flow hypothesis