Answer:
stomach acids to help break down the food
Answer: alleles
Explanation:
Alleles are different forms of a given gene. Alleles are mutated forms of a given gene which controls a particular trait. For instance, the gene that codes for hemoglobin is denoted with the letter A but the gene has another variant denoted by S. In abnormal hemoglobin S (sickle hemoglobin), glutamate is replaced by valine at position 6 in the amino acid sequence of the two beta chains of hemoglobin. This change in the amino acid sequence causes the red blood cells to have a sickle shape resulting in sickle cell disease. Therefore hemoglobin A and S are alleles of a given gene.
The biosphere is the worldwide sum of all ecosystems. Biodiversity is the variation of genetic species in the ecosystem.
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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.