Candidate surname Other names
Centre Number Candidate Number
Paper
B ■ ■
Advanced
PAPER 3: General and Practical Principles in Biology
Marks
Scientific calculator, HB pencil, ruler
Instructions
• Use black ink or ball‑point pen.
centre number and candidate number.
Answer the questions in the spaces provided –
there may be more space than you need.
Information
• The total mark for this paper is 120.
– use this as a guide as to how much time to spend on each question.
In question(s) marked with an asterisk (*), marks will be awarded for your ability to structure
your answer logically, showing how the points that you make are related or follow on from
each other where appropriate
Advice
• Read each question carefully before you start to answer it.
• Check your answers if you have time at the end.
Turn over
, Answer ALL questions.
1 A student made a root tip squash to observe the stages of mitosis.
(a) Name the region of the root tip where cells are actively dividing.
(1)
............................................................................................................................. .. .......................................... ..................................................................................... ......................
(b) Give one reason for each of the following:
(i) Treating the root tip with strong acid
(1)
............................................................................................................................. .. ............................................................................................................................. .. ......................
............................................................................................................................. .. ............................................................................................................................. .. ......................
............................................................................................................................. .. ............................................................................................................................. .. ......................
(ii) Adding a stain to the root tip
(1)
............................................................................................................................. .. ............................................................................................................................. .. ......................
..................................................................................................... .......................... ............................................................................................................................. .. ......................
......................................................................... ...................................................... ............................................................................................................................. .. ......................
(iii) Pressing lightly on the coverslip
(1)
............................................................................................................................. .. ............................................................................................................................. .. ......................
............................................................................................................................. .. ................................................................................................... ............................ ......................
............................................................................................................................. .. ............................................................................................................................. .. ......................
2
■■■■
, (c) The diagram shows cells from a root tip squash. The
total number of cells is 39.
Calculate the mitotic index for this root tip squash. Use
the formula
number of cells in mitosis
Mitotic index = × 100
total number of cells
Give your answer to one decimal place.
(2)
Answer ..............................................................
(Total for Question 1 = 6 marks)
3
■■■■ Turn over
, 2 The mammalian kidney contains over one million nephrons.
One of their functions is to produce urine with a high concentration of urea.
(a) The diagram shows one nephron, collecting duct and some of the associated blood
vessels.
A
(i) Explain how urea enters the nephron.
(2)
............................................................................................................................. .. ............................................................................................................................. .. ......................
............................................................................................................................. .. ................................................................................................... ............................ ......................
............................................................................................................................. .. ....................................................................... ........................................................ ......................
............................................................................................................................. .. ........................................... .................................................................................... ......................
............................................................................................................................. .. ............................................................................................................................... ......................
.................................................................................................................... ........... ............................................................................................................................. .. ......................
4
■■■■
Centre Number Candidate Number
Paper
B ■ ■
Advanced
PAPER 3: General and Practical Principles in Biology
Marks
Scientific calculator, HB pencil, ruler
Instructions
• Use black ink or ball‑point pen.
centre number and candidate number.
Answer the questions in the spaces provided –
there may be more space than you need.
Information
• The total mark for this paper is 120.
– use this as a guide as to how much time to spend on each question.
In question(s) marked with an asterisk (*), marks will be awarded for your ability to structure
your answer logically, showing how the points that you make are related or follow on from
each other where appropriate
Advice
• Read each question carefully before you start to answer it.
• Check your answers if you have time at the end.
Turn over
, Answer ALL questions.
1 A student made a root tip squash to observe the stages of mitosis.
(a) Name the region of the root tip where cells are actively dividing.
(1)
............................................................................................................................. .. .......................................... ..................................................................................... ......................
(b) Give one reason for each of the following:
(i) Treating the root tip with strong acid
(1)
............................................................................................................................. .. ............................................................................................................................. .. ......................
............................................................................................................................. .. ............................................................................................................................. .. ......................
............................................................................................................................. .. ............................................................................................................................. .. ......................
(ii) Adding a stain to the root tip
(1)
............................................................................................................................. .. ............................................................................................................................. .. ......................
..................................................................................................... .......................... ............................................................................................................................. .. ......................
......................................................................... ...................................................... ............................................................................................................................. .. ......................
(iii) Pressing lightly on the coverslip
(1)
............................................................................................................................. .. ............................................................................................................................. .. ......................
............................................................................................................................. .. ................................................................................................... ............................ ......................
............................................................................................................................. .. ............................................................................................................................. .. ......................
2
■■■■
, (c) The diagram shows cells from a root tip squash. The
total number of cells is 39.
Calculate the mitotic index for this root tip squash. Use
the formula
number of cells in mitosis
Mitotic index = × 100
total number of cells
Give your answer to one decimal place.
(2)
Answer ..............................................................
(Total for Question 1 = 6 marks)
3
■■■■ Turn over
, 2 The mammalian kidney contains over one million nephrons.
One of their functions is to produce urine with a high concentration of urea.
(a) The diagram shows one nephron, collecting duct and some of the associated blood
vessels.
A
(i) Explain how urea enters the nephron.
(2)
............................................................................................................................. .. ............................................................................................................................. .. ......................
............................................................................................................................. .. ................................................................................................... ............................ ......................
............................................................................................................................. .. ....................................................................... ........................................................ ......................
............................................................................................................................. .. ........................................... .................................................................................... ......................
............................................................................................................................. .. ............................................................................................................................... ......................
.................................................................................................................... ........... ............................................................................................................................. .. ......................
4
■■■■
