Question

what is a chromosomal mutation?
a a change in the number or structure of chromosomes
b a temporary change that disappears after one cell division
c a mutation that never affects the phenotype
d a mutation involving only one nucleotide

question 14
what does a karyotype show?

a an individual’s chromosomes from one cell
b the nucleotide sequence of a single gene
c all the genes that are expressed in a cell
d an individual’s cellular proteins

question 15
how many total chromosomes are found in a normal human karyotype?

a 92
b 46
c 30
d 44

Explanation:

Question: What is a chromosomal mutation?

• Option a: Chromosomal mutations involve changes in chromosome number (e.g., aneuploidy) or structure (e.g., deletions, translocations), so this matches the definition.
• Option b: Chromosomal mutations are not temporary; they are heritable (in germ cells) or affect cell lines (in somatic cells) and don’t disappear after one division.
• Option c: Chromosomal mutations often affect phenotype (e.g., Down syndrome from trisomy 21).
• Option d: Mutations involving one nucleotide are point mutations, not chromosomal.

• Option a: A karyotype is a visual representation of an individual’s chromosomes (from one cell, typically during metaphase) arranged by size, banding, etc.
• Option b: Karyotypes don’t show nucleotide sequences of genes (that’s DNA sequencing).
• Option c: Karyotypes don’t show expressed genes (that’s related to gene expression analysis, like RNA sequencing or proteomics).
• Option d: Karyotypes don’t show cellular proteins (proteins are studied via protein analysis techniques).

• Normal human somatic cells have 46 chromosomes: 22 pairs of autosomes and 1 pair of sex chromosomes (XX or XY). So a normal karyotype shows 46 chromosomes.
• Option a (92) would be if cells were diploid and duplicated (but karyotypes show chromosomes in a single set, or the diploid complement as 46, not 92).
• Option c (20) is incorrect; humans have 23 chromosome pairs (46 total).
• Option d (44) would be just autosomes (22 pairs), missing sex chromosomes.

Answer:

a. A change in the number or structure of chromosomes

Question: What does a karyotype show?