Which of the following is true of vectors?

a. must be able to replicate autonomously & usually linear (to prevent degradation by host enzymes) and are very small
b. must be able to replicate autonomously & usually circular (to prevent degradation by host enzymes) and can't be too large (fragile) or too small to accept foreign dna

The correct answer is b. must be able to replicate autonomously & usually circular (to prevent degradation by host enzymes) and can't be too large (fragile) or too small to accept foreign DNA

Explanation:

Vectors are plasmids which are used to transfer the desired gene fragment to its host body. Plasmids are extra-chromosomal genetic material present in bacteria and some eukaryotes that have the ability to self replicate.

Plasmids have the ability to transfer genes to other cells and this property of plasmids are used by scientist in cloning experiments so these plasmids are called vectors or plasmid vectors.

The circular form of plasmids does not allow the enzyme to get a site for degradation so its circular form prevents its degradation in the host body. Therefore the right answer is b.

the major parts of the digestive system:

salivary glands.

pharynx.

esophagus.

stomach.

small intestine.

large intestine.

rectum.

accessory digestive organs: liver, gallbladder, pancreas.

sulfur dioxide

explanation: acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. these substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.