Read the passage about horseflies and tularemia below.
Horseflies are large, biting insects whose females feed on the blood of mammals and birds. The horsefly (Tabanus species) is a well-known vector that can transmit the bacterium Francisella tularensis, which causes the disease tularemia.
During their life cycle, female horseflies feed on various hosts to obtain the protein required for egg production. They commonly feed on rabbits (which are herbivores feeding on grass and leafy vegetation) as well as shrews (which feed on herbivorous beetles and caterpillars). Female horseflies can also bite humans, transmitting the bacterium. If a pregnant woman is infected, the bacteria can sometimes cross into the fetal circulation, potentially leading to congenital infection and developmental complications.
Currently, researchers are investigating vaccines to prevent tularemia in high-risk individuals, alongside ecological methods to manage horsefly populations.
Use this information and your biological knowledge to answer the following questions.
The pathogen that causes tularemia is a bacterium. State two cellular structures that are found in all bacteria.
Name the organ that pathogens must cross to get from the mother's blood into the blood of the developing fetus.
Explain how vaccinating a person against the tularemia bacterium protects them from developing the disease if they are bitten by an infected horsefly.
Explain why horseflies can be described as both secondary consumers and tertiary consumers in this food web.
