step assessment

Question 1

Recall Question

Which organelle do you think is shown in the electron micrograph below?
Image

A. Golgi Apparatus
B. Ribosome
C. Nucleolus
D. Mitochondrion

Answer 1

D. Mitochondrion

Question 2

Recall Question

Which organelle listed below is not bound by a membrane?
A. Centriole
B. Chloroplast
C. Nucleus
D. Smooth endoplasmic reticulum

Answer 2

A. Centriole

Question 3

Recall Question

Which of these structures modifies complete proteins to produce glycoproteins?
A. Rough endoplasmic reticulum
B. Smooth endoplasmic reticulum
C. Golgi Apparatus
D. Mitochondria

Answer 3

C. Golgi apparatus

Question 4

Recall Question

Which function does a lysosome carry out?
A. Produces enzymes which digest damaged organelles and foreign matter.
B. Transports hydrophobic lipids around the cell.
C. Produces steroid hormones and cholesterol.
D. Froms a protective envelope around the nucleus.

Answer 4

A. Produces enzymes which digest damaged organelles and foreign matter.

Question 5

Recall Question

Which description below is not true of prokaryotic cells?
A. They store their genetic material in the form of DNA.
B. They have more chloroplasts per cell on average than eukaryotic cells do.
C. They have cell walls made of murein (also known as peptidoglycan).
D. They are usually smaller than eukaryotic cells.

Answer 5

B. They have more chloroplasts per cell on average than eukaryotic cells do.

Question 6

Recall Question

Which of these is not found in any prokaryote?

A. Plasmids
B. Capsule
C. Flagella
D. Mitochondria

Answer 6

D. Mitochondria

Question 7

Recall Question

Which unit would be most appropriate for measuring the length of an average plant cell?

A. am (attometres)
B. mm (milimetres)
C. nm (nanometres)
D. um (micrometres)

Answer 7

D. um (micrometres)

Question 8

Recall Question

Why can a light microscope not produce useful images at greater than 1500x magnification?
A. The magnification is limited by our ability to perfect the fine shape of lenses.
B. It is not possible to cut slices of tissue thin enough without destroying cellular structure.
C. The wax used for embedding tissue samples distorts light too much at higher magnifications.
D. The resolution is limited by the wavelength of light waves.

Answer 8

D. The resolution is limited by the wavelength of light waves.

Question 9

Recall Question

Students measure a structure as 12mm long when studied under the microscope. Its actual size is 29.7 um. What approximate magnification is being used?

A. 40x
B. 360x
C. 400x
D. 3600x

Answer 9

C. 400x

Question 10

Maths Skills

Convert the following numbers from standard form into decimal notation.

1. 3.26 x 10⁴
2. 8.4 x 10^-3

Answer 10

1. 32600
2. 0.0084

Question 10

Exam Question

Place a tick in the box next to the sequence that shows the correct order of magnitude of these measurements.

50nm < 0.5μm < 5 x 10^-2mm < 0.5 x 10^-5m
50nm < 0.5μm < 0.5 x 10^-5m < 5 x 10^-2mm
0.5μm < 50nm < 0.5 x 10^-5m < 5 x 10^-2mm
0.5μm < 50nm < 5 x 10^-2mm < 0.5 x 10^-5m

Answer 10

0.5μm < 50nm < 5 x 10^-2mm < 0.5 x 10^-5m

Question 11

Maths Skills

Using the formula 2 x 3.14 x radius and given that the mean radius of the earth is 6378000m, calculate the approximate circumference of the Earth leaving your answer in standard form to two significant figures.

Answer 11

4.0 x 10⁷

Question 11

Exam Question

Identify structures labelled D and E.

Answer 11

D = Granum
E = Starch

Question 12

Maths Skills

There are 86400 seconds in a day. Calculate the number of seconds in a year leaving your answer in standard form to two significant figures.

Answer 12

3.2 × 10⁷

Question 12

The details shown above would not be seen using an optical microscope.
Explain why.

Answer 12

1. Has low resolution
2. Because wavelength of light is too long

Question 13

Maths Skills

The current world population is approximately 7.4 x 10⁹. The united kingdom population accounts for 0.88% of the total world population. Using this information, approximate the number of people living in the united kingdom leaving your answer as a decimal number.

Answer 13

6.512 × 10⁷

Question 13

Name an organelle found in both a chloroplast and a prokaryotic cell.

Answer 13

(70S) Ribosome.

Question 14

Place a tick in the box that shows the correct order of magnitude of these measurements.

50nm < 0.5μm < 5 x 10^-2mm < 0.5 x 10^-5m
50nm < 0.5μm < 0.5 x 10^-5m < 5 x 10^-2mm
0.5μm < 50nm < 0.5 x 10^-5m < 5 x 10^-2mm
0.5μm < 50nm < 5 x 10^-2mm < 0.5 x 10^-5m

Answer 14

0.5μm < 50nm < 5 x 10^-2mm < 0.5 x 10^-5m

Question 14

Exam Question

Volume of plant cell = 17, 500μm³. Volume of all mitochondria in plant cell = 262.5μm³. Volume of all mitochondria and all chloroplasts in plant cell = 44.1% of volume in plant cell. Use info to calculate volume of all chloroplasts in a plant cell.

Answer 14

44.1% of 17, 500 = 17, 500 x 0.441 = 7717.5μm³ - 262.5μm³ = 7455μm³.

Question 15

The diagram below is an electron micrograph of a chloroplast.

Identify structures labelled D and E

image

Answer 15

D = granum
E = starch

Question 15

Exam Question

A biologist separated cell components to investigate organelle activity. She prepared a suspension of the organelles in a solution that prevented damage to the organelles.

Describe three properties of this solution and explain how each property prevented damage to the organelles.

Answer 15

1. COLD - to reduce enzyme activity that might break down the organelles
2. ISOTONIC - to prevent lysis of organelles as a result of osmotic gain or loss of water
3. BUFFERED- so that the pH does not fluctuate-prevents denaturing of enzyme/proteins

Question 16

Exam Question

Suggest why preventing the formation of spindle fibres stopped the cell cycle. (2)

Answer 16

• centromeres cannot attach
• so no metaphase

Question 17

Exam Question

Suggest and explain why ABZ could be used as a treatment for cancer even though it affects some healthy cells. (1)

Answer 17

• cancer cells divide more rapidly

Question 18

Exam Question

What can you conclude about the effect of ABZ on tumour cells? (4)

ABZ stopped mitosis by preventing the formation of spindle fibres, and it also affected some healthy cells.

Mitosis is controlled. Cyclin B is a protein in the nucleus. It regulates mitosis timing. M starts when CB conc rises sharply and ends when it falls. ABZ increased, and maintained, a high concentration of cyclin B in stomach tumour cells.

Programmed cell death = apoptosis. Two nuclear proteins, Bcl-2 and Bax control apoptosis. Apop is prevented when the Bcl-2 and Bax ratio is high, and is promoted when the ratio is low. The scientists found that ABZ decreased conc of Bcl-2 and increased Bax in stomach tumour cells.

Answer 18

• ABZ maintains Cyclin B
• so mitosis starts but does not end, so no tumour growth
• ABZ lowers ratio of Bcl-2 to Bax
• so apoptosis occurs and no tumour growth

Question 19

# Exam Question Evaluate the suggestion that ABZ could be used for the successful treatment of stomach cancer. (3)

Answer 19

SUPPORT: - stops mitosis so no tumour growth AGAINST - healthy cells damaged - these results are from laboratory tests, not clinical trials involving people.

Question 20

# Exam Question Structures A to E are parts of a plant cell. A- Cell Wall B- Chloroplast C- Nucleus D- Mitochondrion E- Golgi apparatus Complete Table 1 by putting the correct letter, A, B, C, D or E in the box next to each statement.

Answer 20

Has stacked membranes arranged in parallel and contains DNA = Chloroplast (B) Is made of polysaccharide = Cell wall (A) Is an organelle and is not surrounded by two membranes = Golgi apparatus (E)

Question 21

# Exam Question Human breast milk is produced and secreted by gland cells. These gland cells have adaptations that include many mitochondria and many Golgi vesicles. The milk contains a high concentration of protein. Explain the role of these cell adaptations in the production and secretion of breast milk.

Answer 21

Mitochondria release energy in the form of ATP for vesicle transportation. Golgi Vesicles transport the protein out of the cell.

Question 22

Figure box 3 shows part of a prokaryotic cell. Figure 3 0 4 . 1 Name the structures labelled W to Z in Figure 3.

Answer 22

W - (cell surface) membrane X - cell wall Y - capsule Z - flagellum

Question 23

# Exam Question Name the main biological molecule in: W & X

Answer 23

W - Phospholipids; X - Murein / glycoprotein;

Question 24

# Exam Question Name the process by which prokaryotic cells divide.

Answer 24

Binary fission

Question 25

# Exam Question Some prokaryotic cells can divide every 30 minutes. A liquid culture contained a starting population of 1.35 × 104 cells. Assuming each cell divides every 30 minutes, calculate how many cells there will be after 3 hours. Assume no cells die during this time.

Answer 25

8.64 x 10₅

Question 26

# Exam Question Describe how you would use cell fractionation techniques to obtain a sample of chloroplasts from leaf tissue. Do not include in your answer information about any solutions.

Answer 26

1. Macerate / homogenise / blend / break tissues / cells (in solution); 2. Centrifuge; 3. At different / increasing speeds until chloroplast fraction obtained;

Question 27

# Exam Question Table 3 shows features of a mitochondrion and a chloroplast. Complete Table 3 with ticks where a feature is present.

Answer 27

Double Outer Memb: both yes Starch Grains: mit no, chloroplast yes Diff Oxygen into Org: yes mit, no chloro

Question 28

# Exam Question Give the function of a mitochondrion.

Answer 28

to produce energy through cellular respiration.

Question 29

# Exam Question Scientists investigated the effect of an exercise programme on the number and size of mitochondria in skeletal muscle. They took samples of muscle from a large number of volunteers before and after the exercise programme. From each sample, they cut thin sections and used these to determine the mean number of mitochondria per μm2 and the mean area of inner mitochondrial membranes. Their results are shown in Figure 7 and Figure 8. What do the data in Figure 7 and Figure 8 suggest about the effect of the exercise programme on mitochondria? [2 marks]

Answer 29

1. Training made no difference to number (of mitochondria per μm 2. Training led to an increase in the area (of inner mitochondrial membrane);