True very much ..............
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.
Photosynthesis can be defined as the process by which green plants manufacture their food. Photosynthesis is important not only to plants themselves but also to animals, which depend on plants for food.
Answer:
A. A majority of scientists agreed with it
Explanation:
The famous theory called the theory of common descent, states that all the living organisms of the earth have arisen from a common ancestor. This notion was first proposed by a French mathematician,Louis Maupertuis duirng 1740s who was of the view that all organisms had a single ancestor and evolutionary process with the passage of time resulted in the specie diversification.
After that, in 1790s another philosopher Immanuel Kant, suggested that all organisms seem to have a common ancestor. In the same period of 1790s, another scientist , Erasmus Darwin who was the grandfather of Charles Darwin also suggested that all the organisms might have a single ancestor who went through the process of evolution to bring all the majesty into life.
Charles Darwin was the first scientist who worked on this notion for alot of time and proposed the theory of common descent,in his book, On the Origin of Species.
After it, many scientists got agree with this theory such as, Vernon Kellogg in 1907 and T. Ryan Gregory in 2008 and many others explain that no reliable observations exists which contradicts the theory of common descent.
Therefore, option A is the best option.
Hope it helps!