Because the have hollow bones, feathers, wings, beaks, and they lay eggs
Answer:
CG
Explanation:
I'm not 100%, but I do believe that is correct.
Answer:
a. Only the DNA of β cells contains the gene for insulin; only the DNA of chief cells contains the gene for pepsinogen
Explanation:
As stated in the question above, insulin production is exclusive to β cells in the pancreas. This is because only these cells have a gene that manages the production and excretion of insulin within an organism. Similarly, only the main cells of the stomach have the capacity to produce pepsinogen, which indicates that the gene responsible for managing this production is unique to these cells.
Answer:
D. There is no enough oxygen in the culture fluid
Explanation:
The cells in the test tube need to carryout one of the important metabolic processes of living organisms - respiration. The process involves the breakdown of glucose to generate energy for other metabolic processes in the cell.
Respiration can be carried out in the presence of oxygen (aerobic) or in the absence of oxygen (anaerobic). Human cells are primarily aerobic but can carryout respiration anaerobically in the presence of inadequate oxygen.
For aerobic respiration, glucose is broken down in the presence of oxygen to produce carbon-dioxide, water and energy in the form of ATP:

<em>In the absence of oxygen, the glucose becomes converted to lactic acid and a smaller amount of ATP is produced as compared to aerobic respiration.</em>
<em>Hence, lactic acid gradually builds up in the absence of oxygen due to anaerobic respiration.</em>
The correct option is D.