Answer:
At least 17 PCR cycles or 16 PCR cycles
Explanation:
As we know -
In one chain of heating and cooling of polymerase chain reaction (PCR), the strands of DNA gets doubled.
The general mathematical representation of this is

where "n" is the number of PCR cycles.
It is given that DNA strands to be produced is 16 times the original quantity of DNA.
So the PCR cycle must be carried out at least 17 times in order to have DNA strand not less than 16 times the original quantity of DNA
Answer:
The missing step is oxygen is removed from the water after step 3.
Explanation:
The steps listed by Xavier are:
- <em>Water is drawn in trough pores and enters the central cavity.
</em>
- <em>Food is filtered and digested.
</em>
- <em>Water leaves trough an opening at the top of the body.</em>
Porifera or sponges are aquatic, immobile invertebrates whose structure is saccular with an upper opening, the osculus.
Sponges absorb water through their pores, where the porocytes are found, and through flagellated cells -the coanocytes- the movement that allows the entrance of water to the spongocele or atrium is produced, in addition to the phagocytosis of organic elements.
Once the water is in the interior chamber of the sponges, the organic particles are phagocyted to be digested, and the oxygen is removed from the water, and passes through diffusion into the cell. The waste products, as well as carbon dioxide, are released into the water that will be expelled through the osculus.
<u><em>In Xavier's list, the missing step is the removal of oxygen from the water, before it is expelled from the body of the sponge</em></u><em>.</em>
<em />
Learn more:
Sponge structure brainly.com/question/11256747
Some examples could be Giraffes with long necks and the darkening of London's peppered moths after the industrial revolution. Direct selection is the shift of the population of one species towards a certain phenotype. -reference.com
Answer:
Decreasing.
Explanation:
Last year= 10 goldfish
This year= 5 goldfish
The amount in goldfish is decreasing.
I believe it’s the first, third and fourth ones. I might be wrong and I’m sorry if I am.