Answer:Valves stop blood flowing backwards
Explanation: Valve are flags of tissue that control the direction of the blood in our heart.,it prevent the backwards flow of blood. valves regulate blood from flowing back into the atria.The right and left atrio-ventricular valves prevent blood from flowing backwards into atria. When the ventricle is full,the valve prevent backwards flow of blood.
Answer:
The researcher's claim is in the same way of the observation made because from it it is inferred that in a population of bacteria with genetic variation, in which some of them have plasmids and others do not, the population survives because those bacteria with plasmids are resistant to antibiotics, if for example there were only bacteria without plasmids all bacteria would die when using antibiotics so this is an example that genetic diversity is an evolutionary advantage
B. Consumers depend on producers to make food using sunlight. This is the right option.
<span>The second statement is correct. Viruses can infect all cellular life forms, but each cellular species
can be infected by own limited specific range of viruses. Most viruses that harm
animals can not harm humans. But, some viruses can infect different species of mammals, for example both
bats and humans can be infected be rabies.</span>
