Question

1. dna is most known for carrying our genetic code, but in actuality, only about 1% of total dna plays this role. this \coding dna\ is divided into \genes\—sections of dna that code for specific proteins. if you think of dna as a cookbook and of proteins as the dishes, then the genes are the recipes. these recipes are numerous; it’s estimated that humans have around 20,000 genes. they can also be very lengthy; our genes range in size from a few hundred \bases\ to over a million. despite our thousands of genes, there isn’t much genetic variability among us. in fact, over 99% of our genes’ base sequences are identical from person to person. however, in that less-than-1% remainder, variations in the base sequences occur. these variations are what account for our genetic differences.

what percentage of our genes vary from person to person?
a. around 99%
b. around 50%
c. around 1%
d. around 0.01%

1. dna lives in the nucleus of a cell, but the protein-building \machinery\ lives outside the nucleus. the dna is too large to fit through the pores in the nuclear membrane, so a \molecule\ called

na\ acts as messenger, delivering dna’s code. rna, like dna, is composed of four bases with a sugar and phosphate backbone. but unlike dna, it has only one side, taking the shape of a single \helix\. in a process called transcription, sections of dna code are copied into the rna. these short, single-stranded copies then slither through the porous nucleus membrane. once outside the nucleus, the rna enters one of the cell’s ribosomes. these structures
ead\ the code and follow it, collecting the specified amino acids needed to build the protein. while rna is less well-known than dna, it’s equally essential to \heredity\. without it, the dna code would be useless.

if dna is a cookbook to build proteins, what are the ingredients?
a. rna
b. ribosomes
c. helixes
d. amino acids

Explanation:

Question 3

The passage says "over 99% of our genes' base sequences are identical from person to person" and "in that less - than - 1% remainder, variations in the base sequences occur". So the percentage of genes that vary from person to person is around 1%.

The passage states "These structures ('ribosomes') 'read' the code and follow it, collecting the specified amino acids needed to build the protein". If DNA is a cookbook to build proteins, then the ingredients (what is needed to build the protein) are amino acids.

Answer:

C. Around 1%

Question 4