7 Prac stuff Microscopy and Cells (Ass 4)

Question 1

How do you convert mm to um?

Answer 1

x by 1000

Question 2

q1 The photomicrograph shows onion cells. the actual length of the onion cell labelled Y is 350 um and the image length is 140 mm.What is the magnification of the photomicrograph?

Answer 2

x400

Question 3

How does wavelength affect microscopy?

Answer 3

A shorter wavelength gives better resolution

Question 4

A specimen of plant tissue is observed twice with a microscope, first using a red light with wavelength of 650nm and then with green light using wavelength of 510nm what happens to the magnification & resolution when using green light compared to red light?

Answer 4

With a green light the magnification remains the same as the red light but the resolution increases

Question 5

The mean width of mitochondria in an electron micrograph is 6mm. The magnification of the electron micrograph is x9600. What is the actual mean width of mitochondria?

Answer 5

6 x 10^-4 mm

Question 6

q4 the diagram shows an eyepiece graticule and part of a stage micrometer scale as seen using x100 magnification. what is the correct method for calculating the value of one eyepiece graticule unit in micrometers (um)?

Answer 6

multiply 0.1 by 1000 then divide by 100

Question 7

A student observes a cell using a light microscope. The student then draws the cell. Which items will the student need to calculate the magnification of the drawing? 3

Answer 7

eyepiece graticule, ruler and a stage micrometer scale

Question 8

What cell structure does mRNA pass through to go to the ribosome?

Answer 8

nuclear envelope

Question 9

What is the cell structure that organises microtubules to produce the spindle during cell division?

Answer 9

centrosome

Question 10

What cell structure synthesises polypeptides?

Answer 10

ribosome

Question 11

Describe the appearance of the nuclear envelope

Answer 11

a double membrane interspersed with pores

Question 12

Describe the appearance of the centrosome

Answer 12

non-membrane bound cylindrical structures

Question 13

Describe the appearance of the ribosome

Answer 13

non-membrane bound, spherical structures

Question 14

What statements about light microscopy are always correct? 3

Answer 14

1. The greater resolution of a light microscope, the greater detail can be seen
2. increasing the magnification of a light microscope up to its limit of resolution allows more detail to be seen
3. the shorter the wavelength of light used in a light microscope, the greater the detail that can be seen

Question 15

Is the membrane surrounding a chloroplast single or double?

Answer 15

double

Question 16

Is the membrane surrounding a mitochondrion single or double?

Answer 16

double

Question 17

is the membrane surrounding a nucleus single or double?

Answer 17

double

Question 18

is the membrane surrounding a lysosome single or double?

Answer 18

single

Question 19

Is the membrane surrounding the endoplasmic reticulum single or double?

Answer 19

single

Question 20

q9 the electron micrograph shows a structure found in cytoplasm. What is it?

Answer 20

centriole

Question 21

What is the order of the stages of production and secretion of an enzyme? 4

Answer 21

ribosome->smooth endoplasmic reticulum->vesicle->Golgi body

Question 22

What are 3 structures present in eukaryotic cells?

Answer 22

linear DNA, 80S ribosomes

Question 23

What cell structure contains hydrolytic enzymes?

Answer 23

lysosomes

Question 24

Which cell structures are required for the formation of lysosomes and the hydrolytic enzymes they contain? 3

Answer 24

rough endoplasmic reticulum, Golgi apparatus, mitochondria

Question 25

Which cell structures may contain nucleic acid? 3

Answer 25

cytoplasm, chloroplasts, ribosomes

Question 26

What range of cell diameters is typical for prokaryotic cells?

Answer 26

1 to 5um

Question 27

What are essential structural features of viruses? 5

Answer 27

can’t replicate their own genome

can’t make proteins

non-cellular

protein coat

Can have either DNA or RNA

Question 28

An antibiotic, tetracycline, can affect the way in which human mitochondria function. What explains this effect?

Answer 28

The antibiotic prevents translation by binding to 70S ribosomes

Question 29

What make prokaryotes different from Eukaryotes? 4

Answer 29

1000 times smaller than Eukaryotes (0.1 to 5 um)

Circular DNA

lack double-membrane bound cell organelles

Ribosomes are smaller (70S)

Question 30

What are some examples of prokaryotes? 2

Answer 30

Bacteria and blue green algae

Question 31

What are the defining features of Eukaryotes? 4

Answer 31

larger and more complex than prokaryotes (10-100 um in diameter)

contain a nucleus

Have double-membrane bound organelles

evolved from prokaryotes

Question 32

What are some examples of eukaryotes? 4

Answer 32

plants, animals, protists, fungi

Question 33

The single-celled organism, Thiomargarita namibiensis is 700um in diameter and is enclosed in a cell wall. its genetic material is free in the cytoplasm where it occurs as 1000s of copies of circular DNA. Most of the cell is taken up by a large vacuole. What is it and why?

Answer 33

It’s a plant bc it has an enclosed cell wall & large vacuole

Question 34

what are lysosomes?3

Answer 34

used to break down unwanted substances & old cell organelles

sometimes break down old cells in process of autolysis (self-splitting)

Lower pH level inside cell bc hydrolytic enzymes thrive in acidic conditions

Question 35

what are centrioles? 4

Answer 35

found in centrosomes in animals

involved in formation and movement of cilia

form basal bodies (base section) of cilia & flagella

Act as Microtubule organising centre for these organelles