Quiz 5

Question 1

There are fewer than 100,000 genes in the human genome.

Answer 1

TRUE

-By sequencing the human genome and counting the genes, the number is known to be about 30,000.

Question 2

Resolution is a possible outcome of acute inflammation.

Answer 2

TRUE
- There are several possible outcomes of acute inflammation, with resolution being one of them. Others include suppuration, organisation and chronic inflammation.

Question 3

Skeletal muscle is a common site for metastatic carcinoma.

Answer 3

FALSE

Question 4

Epithelioid cells belong to the mononuclear-macrophage system.

Answer 4

TRUE

-Epithelioid cells are specialised macrophages occurring in response to specific stimuli.

Question 5

Concerning contrast media: MR contrast media have a higher mass number than body tissues.

Answer 5

TRUE

Question 6

Darkly-stained regions of chromosomes are heterochromatin.

Answer 6

TRUE
-When chromosomes are stained with dyes, they appear to have alternating lightly or darkly stained regions. The darkly stained regions are heterochromatin and contain repetitive sequences that are genetically inactive.

Question 7

Down’s syndrome can be caused by a translocation.

Answer 7

TRUE
-An unbalanced translocation of chromosome 21 can lead to having 3 copies of the long arm, which causes Down’s syndrome. It is more commonly caused by trisomy for the whole of chromosome 21.

Question 8

HNPCC is a heredity colorectal cancer syndrome where multiple adenomas are found.

Answer 8

FALSE

-HNPCC is a hereditary colorectal cancer syndrome, however few to no adenomas are found.

Question 9

Radiation dose from a single CT abdomen is approximately the same as that of 10 chest X-rays.

Answer 9

FALSE

-Radiation dose from a single CT abdomen is approximately the same as that of 500 chest X-rays.

Question 10

Chromosomal inversions are lethal.

Answer 10

TRUE
-They would only be lethal if they disrupt an essential gene. Some inversions are found as polymorphisms in the normal population, with no phenotypic effects.

Question 11

Retinoblastoma only occurs in heritable forms.

Answer 11

TRUE
-Retinoblastoma can occur both in heritable and nonheritable forms. Nonheritable forms are usually unilateral and present later, whereas heritable forms are usually bilateral and present earlier.

Question 12

Hydatidiform mole forms from two maternal genomes.

Answer 12

FALSE
-Hydatidiform mole is an example of uniparental diploidy and it forms from two paternal genomes. Ovarian teratoma is an example of uniparental diploidy where 2 maternal genomes are combined.

Question 13

If the base sequence of a short section of one strand of a double helix is 5’-ATGGGCTATA-3’, then the sequence on the opposing, complementary strand is 5’-TATAGCCCAT-3’.

Answer 13

TRUE

-Notice, in the statement, that both sequences are written left-to-right in a 5’ to 3’ direction.

Question 14

In meiosis daughter nuclei are not genetically identical to the parent cell.

Answer 14

TRUE

Question 15

In genetics, when drawing a pedigree, consanguinity is indicated with a single horizontal line.

Answer 15

FALSE

-When drawing a pedigree, consanguinity is indicated with a single horizontal line.

Question 16

In DNA, there are three H-bonds between adenine and thymine and two H-bonds between guanine and cytosine.

Answer 16

FALSE
- Part of the stability of double-stranded DNA comes from H-bonding between the specific complementary bases. There are two bonds between adenine and thymine and three between guanine and cytosine.

Question 17

Barium enema is used to visualise the oesophagus.

Answer 17

FALSE

-Barium enema is used to visualise the large bowel. Barium swallow can be used to visualise the oesophagus.

Question 18

The founder effect is defined as random fluctuation of one allele transmitted to high proportion of offspring by chance.

Answer 18

FALSE
-This definition is of genetic drift. The founder effect is defined as the reduction in genetic variation that results when a small subset of a large population is used to establish a new colony.

Question 19

If the base sequence of a short section of one strand of a double helix is 5’-ATGGGCTATA-3’, then the sequence on the opposing, complementary strand is 5’-TACCCGATAT-3’.

Answer 19

FALSE
-Notice, in the statement, that both sequences are written left-to-right in a 5’ to 3’ direction. The correct sequence for the complementary strand is 5’-TATAGCCCAT-3’.

Question 20

Mast cells belong to the mononuclear-macrophage system.

Answer 20

FALSE
-Mast cells come from bone marrow and go into all tissues of the body. Each mast cell contains secretory granules (storage sacs), each containing powerful biologically active molecules called mediators.

Question 21

X-linked alleles are passed from fathers to their daughters.

Answer 21

TRUE
-Males pass their X chromosome to their daughters and a Y chromosome to their sons. Mothers pass one of their 2 X chromosomes to each of their children.

Question 22

In SPECT, gamma cameras stay in place to focus on an area of interest.

Answer 22

FALSE

-In SPECT, gamma cameras rotate around area of interest - it is like a “CT version of nuclear medicine”.

Question 23

In FISH (Fluorescent in situ hybridisation), centromeric probes are useful for detecting translocations.

Answer 23

FALSE
-In FISH, centromeric probes are useful for determining chromosome number. Whole chromosome probes are used to detect translocations.

Question 24

Restriction enzymes are used to diagnose genetic disease by analysing protein samples.

Answer 24

FALSE
-Restriction enzymes (also known as restriction endonucleases) digest DNA, not protein, at specific base sequences. This can be used for DNA cloning and also for analysis when followed by gel electrophoresis.

Question 25

Several assumptions underlie Hardy-Weinberg Equilibrium and account for the differences between expected and observed populations.

Answer 25

TRUE
-There are several assumptions underlying Hardy-Weinberg Equilibrium, for example: mating is random, population size is large, migration is negligible, etc. All of this helps explain the difference between expected population (as per HWE) and observed population (what is actually seen in real life).

Question 26

If the base sequence of a short section of one strand of a double helix is 5’-ATGGGCTATA-3’, then the sequence on the opposing, complementary strand is 5’-TATAGCCCAT-3’.

Answer 26

TRUE

-Notice, in the statement, that both sequences are written left-to-right in a 5’ to 3’ direction.

Question 27

During DNA replication, DNA is synthesised in a 5’ to 3’ direction, and a DNA template is ‘read’ in a 3’ to 5’ direction.

Answer 27

TRUE
-As DNA (and nucleic acids in general) are synthesised when the 5’ C of an incoming monomer is linked to the 3’ C of the monomer at the 3’ end of the chain, the directionality of polymerisation is always 5’ to 3’. The template is ‘read’ in the opposite direction, so that, during DNA replication, the daughter double helices produced, like the parental double helix, both contain polydeoxyribonucleotides arranged in an antiparallel fashion.

Question 28

SPECT is single proton excretion computed tomography.

Answer 28

FALSE

-SPECT is single photon emission computed tomography.