Question

test questions

1. chromatin is best described as:

a. rna molecules attached to ribosomes
b. dna and proteins organized into a compact complex
c. lipid - protein layers forming chromosomes
d. single - stranded rna - dna hybrids

1. the physical location of a gene on a chromosome is called its:

a. chiasma
b. locus
c. allele
d. karyotype

1. a karyotype is used primarily to:

a. measure transcriptional activity
b. detect chromosomal abnormalities
c. analyze nucleotide composition
d. identify enzyme deficiencies

1. homologous chromosomes can be distinguished by:

a. differences in gene function only
b. similar banding pattern, size, and centromere position
c. identical sequence with no variation
d. distinct histone composition

1. the y chromosome differs from the x chromosome because it:

a. has no genes in common with the x chromosome
b. contains short regions of homology but is otherwise distinct
c. always pairs completely with the x chromosome
d. is transcriptionally inactive in males

1. the chromosomal material in prokaryotic cells is found in:

a. the nucleoid region
b. the nucleus
c. the lysosome
d. the golgi apparatus

1. most eukaryotic organisms are diploid, meaning they:

a. contain two sets of homologous chromosomes
b. contain only one circular chromosome

Explanation:

1. Chromatin is composed of DNA and proteins (histones) organized into a complex. RNA - ribosome complexes are related to translation (not chromatin). Lipid - protein layers are not the main component of chromatin. Single - stranded RNA - DNA hybrids are not the description of chromatin.
2. The locus is the physical location of a gene on a chromosome. A chiasma is related to crossing - over in meiosis. An allele is a variant of a gene. A karyotype is a picture of chromosomes.
3. A karyotype is a visual display of chromosomes and is used to detect chromosomal abnormalities (e.g., extra or missing chromosomes). It does not measure transcriptional activity (which is related to gene expression), analyze nucleotide composition (sequencing is for that), or identify enzyme deficiencies (biochemical tests are more relevant).
4. Homologous chromosomes have similar banding patterns (due to similar gene content and structure), size, and centromere position. They can have different alleles (so gene function can be different in a sense of variant expression). They are not identical in sequence (as there are alleles). Histone composition is similar for homologous chromosomes.
5. The Y chromosome has short regions of homology (pseudo - autosomal regions) with the X chromosome but is otherwise distinct. It is not that there are no common genes. It does not always pair completely (only in pseudo - autosomal regions). It is not transcriptionally inactive in males (e.g., SRY gene is active).
6. Prokaryotic cells (like bacteria) do not have a nucleus. Their chromosomal material is in the nucleoid region. Lysosomes are in eukaryotic cells (for digestion). The Golgi apparatus is also a eukaryotic cell organelle (for protein modification and sorting).
7. Diploid means having two sets of chromosomes (homologous pairs). Having only one circular chromosome is more characteristic of prokaryotes.

Answer:

1. B. DNA and proteins organized into a compact complex
2. B. Locus
3. B. Detect chromosomal abnormalities
4. B. Similar banding pattern, size, and centromere position
5. B. Contains short regions of homology but is otherwise distinct
6. A. The nucleoid region
7. A. Contain two sets of homologous chromosomes