Answer:
An index fossil is also known as guide fossils or indicator fossil. They are fossils used to determine and identify geologic periods.
The main characteristics of an index fossil include :
1.It must be distinctive.
2.It must be widespread.
3. It must be abundant
4. It must be limited in geologic time. 
Due to trends and studies of most fossil-bearing rocks being formed in the ocean, the major index fossils are mostly marine animal or plant organisms.
 
        
                    
             
        
        
        
Answer:
Enterococcus.
Explanation:
Enterococcus is reason for nosocomial infection with predilection for older patients with multiple comorbidities. It is usually caused by longer stay in hospital.  The infections may include urinary tract infections, wound infection and intra abdomen or pelvic infections. 
 
        
             
        
        
        
A is the correct answer, eukaryotic cells have membrane-bound nucleus, prokaryotic cells do not. 
        
             
        
        
        
Answer:
The term transgenic plants refers to the plants whose DNA is modified through genetic engineering. This means that one or several genes from a different species are introduced and combined with the genetic material of the plant which changes the traits of the original genome.
While horizontal gene transfer has been shown to occur naturally in nature (between plants that grow close to each other), various artificial techniques are used to insert gene sequences to some plants with the aim of increasing yields, making them more tolerant of various environmental conditions, or making them more resistant to given biotic stresses, etc.