microbiologymultichoice2

The cytotrophoblast is the inner layer of the trophoblast, interior to the syncytiotrophoblast in an embryo. It serves to anchor the embryonic chorion to the endometrium. These cells invade maternal uterine tissue and thus are in direct contact with maternal stroma and immune cells.

Gastrulation is a phase early in the development of embryos, during which the morphology of the embryo is dramatically restructured by cell migration Gastrulation occurs after implantation, around day 16 after fertilization in human embryogenesis. It essentially changes the embryo so it is protected via the fluid in the amnion layer, and is able to produce its own blood cells, through the yolk sac of the hypoblast.

Created by: troy

What is your age?
Under 18 Years Old
18 to 24 Years Old
25 to 30 Years Old
31 to 40 Years Old
41 to 50 Years Old
51 to 60 Years Old
Over 60 Years Old
What is your gender?
Male
Female
1. which of the following reagents is not used in the PCR amplification reactions
DNA polymerase
Mg ions
dNTPs
primers comprising short ribonucleotide sequence
primers comprising short deoxyribonucleic acids
2. which of the following statements about PCR primers is true
a single primer is requred to initiate PCR from a double stranded template DNA
two primers are required to initiate PCR from a double stranded template DNA
3. PCR amplification from template DNA by thermophilic DNA polymerase is dependent on
a low concentration of dNTPs relative to the template DNA
denaturing template DNA at a maximum 72C
using a single primer to initiate amplification
Using short primers that have annealing temperatures above 72C
none of the above
4. which of the following factors does not affect the annealing temperature of PCR primers?
primer length
base composition
dNTP concentrations
primer concentrations
more than one of the above does not affect annealing termperature
5. which one of the following statements is false
during PCR, the primers become incorperated into the amplified DNA
during PCR, the primers initiate replication but do not become incorperated into the amplifed DNA
primers used in PCR must be present in excess concentrations
the longer the primer, the higher the annealing temperature
the length of the DNA synthesis step in PCR is dependent on the length of the DNA fragment to be annealed
6. PCR can be used in the following applications
creating new restriction enzyme sites in DNA
creating deletion mutations
creating gene fusions
detection of low concentrations of DNA
all of the above
7. which of the following statements concerning overlap extension PCR (OEPCR) is incorrect
OEPCR methods requires three separate PCR reactions
OEPCR methods require the use of only two primers
OEPCR requires the use of four primers
OEPCR can be used to join two DNA sequence together
OEPCR always requires a step in which the primers are removed from the PCR products
8. Oligonucleotide primers are synthesised by which one of the following methods
ligation of dNTPs
chemical synthesis from protected nucleotides
enzymatic synthesis from dNTPs
chemical synthesis from dNTPs
all of the above
9. The most important role of the prokaryotic cell wall is to:
(a) Maintain the shape of the cell.
(b) Protect the cell from changes in osmotic pressures.
(c) Prevent ions from diffusing away from the cell.
(d) Block the effects of antibiotics like penicillin.
(e) Protect bacteria from phagocytosis by eukaryotic cells.
10. Which one of the following statements characterises cell wall complexes of Gram positive bacteria?
(a) Thick, homogeneous cell walls comprising lipopolysaccharide, lipoteichoic acids
(b) Thick, homogeneous cell walls comprising lipoteichoic, teichoic acids and
(c) Thick, homogeneous cell walls surrounded by an outer membrane.
(d) All of the above are characteristics of Gram positive cells.
(e) None of the above are characteristics of Gram positive cells.
11. The outer membrane of Gram negative cells is more permeable than the plasma membrane because:
(a) The outer membrane is attached to the cell membrane in many places.
(b) The core polysaccharide of lipopolysaccharide spans the lipid bilayer.
(c) The lipopolysaccharide component located in the outer leaflet of the outer
(d) Lipoproteins that anchor the outer membrane to the cell membrane alter
(e) Outer membrane proteins can form holes in the outer membrane.
12. The third amino acid in the peptidoglycan cross-linking chain is either diaminopimelic acid or lysine. These di-amino amino acids are in this position because this amino acid must:
(a) Be positively charged for a salt bridge to form.
(b) Be hydrophilic.
(c) Have a large R-side chain to fill space in the cell wall.
(d) Have a free amino group for peptide bond formation.
(e) None of the above
13. Fimbriae (often called pili):
(a) Are used by bacteria as osmoregulatory sensors.
(b) Assist bacteria to attach to the surface of Eukaryotic cell surfaces.
(c) Enable bacteria to move through fluids.
(d) Are used by bacteria to sense changes in nutrient concentration.
(e) Are part of Type III secretion systems designed to secrete of exoenzymes across
14. Which one of the following statements best describes the purpose of endospores produced by bacteria belonging to the genera Bacillus and Clostridium?
(a) Endospores allow the bacterium to form the next generation of bacterial cells.
(b) Endospores help bacteria to differentiate into faster growing stages of bacteria.
(c) Endospores allow these bacteria to survive the absence of oxygen.
(d) Endospores allow these bacteria to survive extended periods of heat or dryness.
(e) Endospores allow these bacteria to grow at elevated temperatures.
15. Which of the following treatments does not kill bacterial endospores?
(a) Autoclave (121ºC at 1 atmosphere pressure for 15 min).
(b) Incineration.
(c) Hot air sterilization (161ºC for 1 h).
(d) Pasteurization (72°C for 30 sec).
(e) All of these processes kill endospores.
16. A bacteriologist obtained the following results from a plate count of bacteria in a sample. Sixty four (64) colonies grew on a nutrient agar plate inoculated with 0.1 ml of sample withdrawn from a solution diluted 1 in 104 in a standard plate count procedure. How many cells were in the original sample?
(a) 640
(b) 6,400
(c) 64,000
(d) 640,000
(e) 6,400,000
17. In order for a polypeptide to be secreted across the cell membrane of a bacterium via the Sec dependent pathway, the peptide must include a sequence of amino acids called a signal (or leader) peptide. Which one of the following is NOT a property of signal peptides?
(a) It assists targeting of the polypeptide to the membrane.
(b) Contains a central H region comprising hydrophobic amino acids.
(c) It is cleaved by a signal peptidase once the peptide is translocated through the
(d) It interacts with the Signal Recognition (SRP) complex.
(e) It is located at the C-terminal end of the polypeptide.
18. Which of the following statements relating to restriction endonucleases is correct:
(a) They cut DNA at random locations.
(b) They recognise specific sequences on RNA.
(c) Their recognition sequences are usually palindromic.
(d) Their recognition sites are unaffected by DNA methylation
(e) May have exonuclease activity.
19. which one of the following statements about the prokaryotic cell wall is correct
protects bacteria from dehydration
protects bacteria from changes in osmotic pressure
prevents ions from diffusing away from the cell
protects the cell from changes in the environmental pH
none of the above
20. which one of the following statements characterises cell wall complexes of gram positive bacteria
thick homogenous cell walls comprising lipopolysaccaride, lipoteichoic acids and peptidoglycan
thick homogenous cell walls comprising lipoteichoic, teichoic acids and peptidoglycan
thick homogenous cell walls surrounding by an outer membrane
all of the above are characteristics of gram positive cells
none of the above is characteristic of gram positive cells

What is your age?

Under 18 Years Old

18 to 24 Years Old

25 to 30 Years Old

31 to 40 Years Old

41 to 50 Years Old

51 to 60 Years Old

Over 60 Years Old

What is your gender?

Male

Female

1. which of the following reagents is not used in the PCR amplification reactions

DNA polymerase

Mg ions

dNTPs

primers comprising short ribonucleotide sequence

primers comprising short deoxyribonucleic acids

2. which of the following statements about PCR primers is true

a single primer is requred to initiate PCR from a double stranded template DNA

two primers are required to initiate PCR from a double stranded template DNA

3. PCR amplification from template DNA by thermophilic DNA polymerase is dependent on

a low concentration of dNTPs relative to the template DNA

denaturing template DNA at a maximum 72C

using a single primer to initiate amplification

Using short primers that have annealing temperatures above 72C

none of the above

4. which of the following factors does not affect the annealing temperature of PCR primers?

primer length

base composition

dNTP concentrations

primer concentrations

more than one of the above does not affect annealing termperature

5. which one of the following statements is false

during PCR, the primers become incorperated into the amplified DNA

during PCR, the primers initiate replication but do not become incorperated into the amplifed DNA

primers used in PCR must be present in excess concentrations

the longer the primer, the higher the annealing temperature

the length of the DNA synthesis step in PCR is dependent on the length of the DNA fragment to be annealed

6. PCR can be used in the following applications

creating new restriction enzyme sites in DNA

creating deletion mutations

creating gene fusions

detection of low concentrations of DNA

all of the above

7. which of the following statements concerning overlap extension PCR (OEPCR) is incorrect

OEPCR methods requires three separate PCR reactions

OEPCR methods require the use of only two primers

OEPCR requires the use of four primers

OEPCR can be used to join two DNA sequence together

OEPCR always requires a step in which the primers are removed from the PCR products

8. Oligonucleotide primers are synthesised by which one of the following methods

ligation of dNTPs

chemical synthesis from protected nucleotides

enzymatic synthesis from dNTPs

chemical synthesis from dNTPs

all of the above

9. The most important role of the prokaryotic cell wall is to:

(a) Maintain the shape of the cell.

(b) Protect the cell from changes in osmotic pressures.

(d) Block the effects of antibiotics like penicillin.

(e) Protect bacteria from phagocytosis by eukaryotic cells.

10. Which one of the following statements characterises cell wall complexes of Gram positive bacteria?

(a) Thick, homogeneous cell walls comprising lipopolysaccharide, lipoteichoic acids

(b) Thick, homogeneous cell walls comprising lipoteichoic, teichoic acids and

(d) All of the above are characteristics of Gram positive cells.

(e) None of the above are characteristics of Gram positive cells.

11. The outer membrane of Gram negative cells is more permeable than the plasma membrane because:

(a) The outer membrane is attached to the cell membrane in many places.

(b) The core polysaccharide of lipopolysaccharide spans the lipid bilayer.

(d) Lipoproteins that anchor the outer membrane to the cell membrane alter

(e) Outer membrane proteins can form holes in the outer membrane.

12. The third amino acid in the peptidoglycan cross-linking chain is either diaminopimelic acid or lysine. These di-amino amino acids are in this position because this amino acid must:

(a) Be positively charged for a salt bridge to form.

(b) Be hydrophilic.

(d) Have a free amino group for peptide bond formation.

(e) None of the above

13. Fimbriae (often called pili):

(a) Are used by bacteria as osmoregulatory sensors.

(b) Assist bacteria to attach to the surface of Eukaryotic cell surfaces.

(d) Are used by bacteria to sense changes in nutrient concentration.

(e) Are part of Type III secretion systems designed to secrete of exoenzymes across

14. Which one of the following statements best describes the purpose of endospores produced by bacteria belonging to the genera Bacillus and Clostridium?

(a) Endospores allow the bacterium to form the next generation of bacterial cells.

(b) Endospores help bacteria to differentiate into faster growing stages of bacteria.

(d) Endospores allow these bacteria to survive extended periods of heat or dryness.

(e) Endospores allow these bacteria to grow at elevated temperatures.

15. Which of the following treatments does not kill bacterial endospores?

(a) Autoclave (121ºC at 1 atmosphere pressure for 15 min).

(b) Incineration.

(d) Pasteurization (72°C for 30 sec).

(e) All of these processes kill endospores.

16. A bacteriologist obtained the following results from a plate count of bacteria in a sample. Sixty four (64) colonies grew on a nutrient agar plate inoculated with 0.1 ml of sample withdrawn from a solution diluted 1 in 104 in a standard plate count procedure. How many cells were in the original sample?

(a) 640

(b) 6,400

(d) 640,000

(e) 6,400,000

17. In order for a polypeptide to be secreted across the cell membrane of a bacterium via the Sec dependent pathway, the peptide must include a sequence of amino acids called a signal (or leader) peptide. Which one of the following is NOT a property of signal peptides?

(a) It assists targeting of the polypeptide to the membrane.

(b) Contains a central H region comprising hydrophobic amino acids.

(d) It interacts with the Signal Recognition (SRP) complex.

(e) It is located at the C-terminal end of the polypeptide.

18. Which of the following statements relating to restriction endonucleases is correct:

(a) They cut DNA at random locations.

(b) They recognise specific sequences on RNA.

(d) Their recognition sites are unaffected by DNA methylation

(e) May have exonuclease activity.

19. which one of the following statements about the prokaryotic cell wall is correct

protects bacteria from dehydration

protects bacteria from changes in osmotic pressure

prevents ions from diffusing away from the cell

protects the cell from changes in the environmental pH

none of the above

20. which one of the following statements characterises cell wall complexes of gram positive bacteria

thick homogenous cell walls comprising lipopolysaccaride, lipoteichoic acids and peptidoglycan

thick homogenous cell walls comprising lipoteichoic, teichoic acids and peptidoglycan

thick homogenous cell walls surrounding by an outer membrane

all of the above are characteristics of gram positive cells

none of the above is characteristic of gram positive cells

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