Answer:
Atmosphere refers to the thin blanket of air that surrounds the earth.
It serves many important functions such as:
- It contains a mixture of gases that are essential for the existence of life on earth. For example, carbon dioxide is essential for photosynthesis and oxygen is essential for cellular respiration.
- It also serves as the reservoir of water in the form of water vapor. Thus, it forms an important constituent for the water cycle.
- It maintains the temperature of the earth. Through the greenhouse effect, it maintains the temperature of the earth in limited ranges.
- It protects the earth from harmful rays of the sun. For example, ozone inhibits the entry of most of the UV rays of the sun into the earth environment.
The answer would be: C) sexual selection.
Sexual selection happens where one of the individuals choose the partner to sex based on some criteria. In this case, the ability to have a beautiful bower will determinate the ability of the bird to have sex and produce offspring. The criteria are not limited to visual. It could be diverse in other cases, like a deeper croak in frog
Chemical methods--It includes ion exchange, precipitation, oxidation and reduction, and neutralization.........
Thermal methods--In this, high-temperature incineration, which not only can detoxify certain organic wastes but also can destroy them....
Biological treatment-- It is of certain organic wastes, such as those from the petroleum industry by a special method called landfarming
Physical treatment-- It concentrates, solidifies, or reduces the volume of the waste. Physical processes include evaporation, sedimentation, flotation, and filtration....
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.