Answer:
Restriction enzymes, also called restriction endonucleases, recognize a specific sequence of nucleotides in double stranded DNA and cut the DNA at a specific location. They are indispensable to the isolation of genes and the construction of cloned DNA molecules.
Answer: B - transports oxygen and carbon dioxide for the respiratory system
The cardiovascular system consists in the heart and all blood vessels. Blood vessels lead the blood from the heart to the rest of the body and then brings it back. It's in the lungs, part of the respiratory system, where the gas exchange is going to happen. What that means is that oxygen is going to enter the blood while the carbon dioxide needs to be eliminated.
(If the option A, said carries hormones FROM the endocrine system, that would be also correct.)
<span>Antibiotics need to be used with caution because of evolution. If you treat bacteria with an antibiotic, some will be resistant by sheer chance. Those ones will survive and go on to divide - producing more antibiotic resistant bacteria. With medical antibiotics, they must be taken for the entire course. Even after symptoms have passed, bacteria remain in the body. If a patient stops taking antibiotics too early, the survivors can keep dividing and cause a new antibiotic resistant infection. With the normal course of medication, antibiotics kill off enough bacteria and keep them at bay long enough for the immune system to finish the job and take care of any resistant stragglers.
The real danger, though, comes from antibiotic use in livestock. It's more cost effective to feed cattle with a constant supply of antibiotics, whether they're sick or not (as opposed to just treating them when they're sick). These antibiotics keep them from getting sick, but it means that eventually bacteria adapt to them and gain resistant. To make matters worse, the antibiotics are often passed from their bodies in their waste, which can go on to contaminate waterways. This can disrupt ecosystems and produce antibiotic-resistant bacteria in the wild. This type of usage is of much more concern because of its scale - there are far more cows on antibiotics than people</span>
They are joined by Surgar-Phosphate Linkage.
Hope this helps