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.
Answer:
An ecological community is made up of all the populations of all the different species that live together in a particular area. The interactions between different species in a community are called interspecific interactions, inter- means "between".
Answer:
Part 1:D) Fertilization
Part 2: C) The process combines genes from two individuals into a distinct organism.
Explanation:
99% sure its correct
Answer:
Channel proteins form hydrophilic channels to passively transport substances down the concentration gradient.
Carrier proteins bind to substances to transport them actively against the concentration gradient. They do not form channels.
Explanation:
Channel proteins are the membrane proteins that serve in transport of small polar molecules and/or ions by making a hydrophilic pore across the membrane. These molecules diffusion through the pore and exhibit facilitated diffusion.
Carrier proteins are the membrane proteins that transport the substances across the membrane by binding to them. They do not form the hydrophilic channels. Carrier proteins serve in the active transport of molecules against the concentration gradient.
Answer: "symbiosis" ; or, a "symbiotic relationship" .
_____________________________________________________________