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Iodine Solution or Reagent / Iodine in KI 1: / - Mark Scheme

This document contains a mark scheme for a biology exam. It provides the answers and marks awarded for 15 multiple choice and short answer questions about various biology topics. The questions cover areas like transport in plant cells, cell structure, diffusion, osmosis, and bacteria. For each question, the mark scheme lists the key points or elements that are required to earn marks. Guidance is also provided to clarify acceptable and unacceptable answers.

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Mira Mohamed Nabil
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69 views5 pages

Iodine Solution or Reagent / Iodine in KI 1: / - Mark Scheme

This document contains a mark scheme for a biology exam. It provides the answers and marks awarded for 15 multiple choice and short answer questions about various biology topics. The questions cover areas like transport in plant cells, cell structure, diffusion, osmosis, and bacteria. For each question, the mark scheme lists the key points or elements that are required to earn marks. Guidance is also provided to clarify acceptable and unacceptable answers.

Uploaded by

Mira Mohamed Nabil
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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- Mark Scheme /

Question Answer Marks AO Element Notes Guidance

1 iodine solution or reagent / 2


iodine in KI;
brown/ orange/ yellow to blue/
purple/ black/ AW;

2 safety - water bath/ AW; 3 max [3]


Benedict's (solution);
heat/boil;
blue/ to green / yellow/ orange/ A brick red
red;

3 1
C - Add iodine solution.
- Mark Scheme /

Question Answer Marks AO Element Notes Guidance

4 functions 6 max 5 from one section


conduct / transport, water (and
mineral ions) ;
ref. to transpiration ;
reduced resistance to water flow
/ AW ;
structural) support (for plant) ;

prevents (inward) collapse (of


xylem vessels) ;
(spirals) allows (some) flexibility
/ bending, of stems (to prevent
breaking) ;
adaptations
long / elongated (cells / vessels
/ tubes) ;
ref. to lignin (in walls) ;
(cell walls) are water
impermeable / waterproof / AW
;
(secondary) thickening of cell
walls ;
hollow / no cytoplasm / no A rings / spirals / AW
(named) organelles ;
no, end / cross, walls (between
cells) ;
end plates to connect vessels
- Mark Scheme /

Question Answer Marks AO Element Notes Guidance

(end to end) ;
pits in walls (for water movement
between vessels) ;

5 55 (µm) ; 1

6 1
C - protein

7 nucleus: 4 max [4]


1 controls (activities) in the cell/ I 'brain' of cell/ 'tells cell
AW; what to do'
2 contains, chromosomes/ MP1 A ref to making
genes/ alleles/ genetic proteins
information/ DNA;
A makes ribosomes
3 controls how cells, develop/
divide/ reproduce/ grow;
cell membrane:
4 forms a barrier/ separates a
cell from surroundings;
5 allows/ controls, movement of e.g. O2/ CO2/
(named) substance(s), across/ nutrients
in/ out;
6 keeps contents of cell inside/
keeps cytoplasm intact/ AW; I ref to shape/ 'covers
cell'/ protects cell
- Mark Scheme /

Question Answer Marks AO Element Notes Guidance

8 composed of (group of) cells 2


with similar structures ;
working together to perform
shared functions ;

9 1
D - increasing the surface area
of the cell membrane

10 (actual length of bacterium) = 1


size / length, of the image ÷
magnification ;

11 passive / does not require 2 max [2]


energy ;
substances move down a
concentration gradient ;
does not have to occur across
a membrane ;
occurs with gases ;
no need for protein, carrier /
channels / pumps ;

–3
12 0.15 mol dm ; 2 units must be
included
no net movement of water / (red
blood) cells will remain normal A (red blood) cells
shape / AW ; won’t be damaged /
isotonic (with solution)
- Mark Scheme /

Question Answer Marks AO Element Notes Guidance

13 active, transport/ uptake; 2 AO1 max [2]


use of energy, ATP (from
respiration);
use of, proteins/ carrier
molecules, in membranes;

14 1
D - The cell shrinks because
water leaves it.

15 B 1

[Total: 30]

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