Diphtheria

Natural infection with C. diphtheriae occurs only in humans and is spread by respiratory droplets. 

The organism colonizes the nasopharyngeal tract and causes little tissue damage, with only a mild inflammatory reaction. 

TLS Online TPP Program

#Id: 5371

#XL - T Zoology

Pitfall traps set into the ground catch wandering species such as beetles and spiders. These have rain covers to prevent the animals from drowning

 

TLS Online TPP Program

#Id: 5372

#XL - T Zoology

Baited snap traps, Population density can thus be estimated as the number of animals caught per trap or per unit area where a given number of traps are set.

TLS Online TPP Program

#Id: 5373

#XL - T Zoology

The mark-recapture technique is that after the tagged animals are released, they mix freely with unmarked individuals. The population is resampled and the numbers of marked and unmarked individuals are recorded. 

TLS Online TPP Program

#Id: 5374

#XL - T Zoology

TLS Online TPP Program

#Id: 5375

#XL - T Zoology

Mark-recapture technique can have drawbacks;

1. Some animals that have been marked may learn to avoid the traps. 
2. Recapture rates will then be low, resulting in an overestimate of population size.

TLS Online TPP Program

#Id: 5376

#XL - T Zoology

Some animals can become trap-happy, particularly if the traps are baited with food. This would result in an underestimate of the population size.