Question 1(b)(i)
[Maximum number: 1]
The diagram shows a forest food web.
The coyote uses some of its senses to catch deer.
Name the sense that uses receptor cells in the retina.
IGCSE Biology 2.91 Glucose homeostasis Topic Practice
2.91 Glucose homeostasis
Describe the structure and function of the eye as a receptor.
Question 2
Question 2(a)
(a)
The diagram shows a human eye.
[ 1 ]
Question 2(a)(i)
(i)
Which labelled structure is the cornea?
[ 1 ]
Question 2(b)
(b)
A student investigates if using one eye or using two eyes is better for judging the distance of objects.
The student uses the plastic block shown in the diagram. The block has a grid where six different coloured pins can be placed as shown in the diagram.
This is the student's method.
- place one pin into the lines of each column and row so that each pin is a different distance from the front of the grid
- ask a volunteer to close one eye
- hold the grid in front of the volunteer so they can see the coloured pins but not the grid
- ask the volunteer to call out the colour of the pins in order of distance, from nearest to furthest
- record the number of pins that the volunteer identifies correctly
- repeat eight more times, each time moving the pins to different positions in the grid
The student does the experiment again with both eyes open.
[ 3 ]
Question 2(b)(iv)
(i)
The field of view is the area that an animal can see with their eyes. The diagram shows the field of view for a cat.
Explain why predators, such as cats, have two forward facing eyes.
Use the information in the diagram and Table 2 to support your answer.
[ 3 ]
Question 2(a)
[Maximum number: 3]
The diagram shows a section through an eye with some parts labelled.
Name parts W, X and Y.
W
X
Y
Question 4
[Maximum number: 5]
The diagram shows a section through a human eye with some structures labelled.
Question 4(a)(i)
(a)
Which structures refract light onto the retina?
A
E and J
B
F and H
C
G and K
D
I and J
[ 1 ]
Question 4(a)(iii)
(b)
Which structure contains light sensitive cells?
A
H
B
I
C
J
D
K
[ 1 ]
Question 4(c)
(c)
Some people develop cataracts in their lenses as they get older.
The diagram shows how a cataract changes the appearance of a person's eye.
CATARACTS
Normal
Eye with Cataract
[ 3 ]
Question 4(c)(i)
(i)
Explain how cataracts affect a person's vision.
[ 2 ]
Question 4(c)(ii)
(ii)
The treatment for a person with cataracts is to remove the affected lenses.
Suggest what additional treatment is needed for the person.
[ 1 ]
Question 3(a)
[Maximum number: 1]
The diagram shows a human eye with some structures labelled.
Which structure is the retina?
A
P
B
Q
C
R
D
S
Question 6(c)(ii)
[Maximum number: 2]
The human liver produces bile.
A scientist investigates the glucose concentration in a person's hepatic portal vein and hepatic vein after the person has eaten a meal.
This is the scientist's method.
- give a person a meal to eat
- after one hour take a blood sample from the hepatic portal vein and a blood sample from the hepatic vein
- measure the glucose concentration in both samples
- after five hours take another blood sample from each of the two veins
- measure the glucose concentration in both samples
The table shows the scientist's results.
After five hours, the concentration of glucose in the hepatic vein is higher than the concentration of glucose in the hepatic portal vein.
Explain this difference in concentration.
Question 7(c)(i)
[Maximum number: 1]
The diagram shows a section through the human eye with parts labelled F to L .
Which structure detects light?
A
F
B
G
C
H
D
J
Question 8
[Maximum number: 6]
The diagram shows a section through the human eye.
Question 8(a)
(a)
Name the structures labelled A, B, C and D.
A
B.
C
D
[ 4 ]
Question 8(b)
(b)
When a person looks directly at an object, light is focused on the fovea of the retina.
[ 2 ]
Question 8(b)(ii)
(i)
Some people develop a condition called age-related macular degeneration (AMD).
This occurs when cells in the fovea of the retina are damaged.
Suggest how AMD affects vision.
[ 2 ]
Question 8(c)
[Maximum number: 3]
Fur colour in rats is controlled by a gene with two alleles.
One allele codes for black fur colour. The other allele codes for agouti fur colour.
Several female rats with agouti coloured fur are mated with several male rats with black coloured fur.
All of the offspring have agouti coloured fur.
Some rats with white fur also have pink eyes.
These rats have pink eyes because they do not have pigment in their irises.
This means that their irises let light pass through, unlike the coloured irises found in other rats.
Explain how this difference in the iris affects vision in the rats with pink eyes.