The correct answer to this question is this one: they lacked oxygen. The earliest organisms were completely heterotrophic in nature because of the reason that they lacked oxygen. <span>A heterotroph is an organism that cannot fix carbon and uses organic carbon for growth. </span>
        
             
        
        
        
You measure temperature with a barometer
        
                    
             
        
        
        
Answer: The correct answer to the question is option C
OSTEOARTHRITIS.
The client has a degenerative form of disease that is evidenced by osteoarthritis.
Explanation: Osteoporosis is otherwise known as degenerative joint disease.
In a healthy joint,a protective cartilage cushions the end of bones(articulating bones) and as well acting as a shock absorber.
In osteoarthritis,these cartilage that acts as a cushion to the bones wears down down or generates with time exposing the joint and the bones predisposing them to mild to moderate friction that occurs as a result of mobility of the bones/joint.
Osteoarthritis mostly affect joints of the hips, hands,spine and knees.
Some of the common symptoms of Osteoarthritis are;pain in the joints of the hands,knees,hips,lower back and neck with crackles,stiffness and tenderness of the joints which often results to difficulty in walking and deformity of the joint if left untreated.
 
        
             
        
        
        
Answer:
a. deterioration of neurons that produce the neurotransmitter acetylcholine.
Explanation: 
Alzheimer's disease -  
It is a disease associated with memory , it is a type of dementia . 
The initial stages of the disease is the remember new things , the day to day task becomes very difficult with time . 
During this disease the neurons get deteriorated day by day , which are responsible to produce the acetylcholine . 
Hence , the correct statement about Alzheimer's disease is ( a ) . 
 
        
             
        
        
        
A cell membrane pump helps human cells to maintain a relatively constant sodium and potassium  concentration.
<u>Option: A</u>
<u>Explanation:</u>
Sodium potassium pump is a plasma membrane protein that utilizes energy ATP — Triphosphate Adenosine turning into ADP — Adenosine Diphosphate to deliver intracellular and extracellular sodium (NA+) and potassium (K+) ions sequentially. The purpose of this entire mechanism is to preserve cell equilibrium.
The extracellular medium has a greater concentration of Na while the K concentration of the intracellular fluid is lower. Proteins trap sodium ions in the cytoplasm and pump them out from the cells to preserve cell stability while preserving concentrations. Within the cells proteins inject potassium ions into the cell.