All MCQs

Open circulation can be adequate for animals with lower metabolic demands. Many bivalves are less active and do not require high-pressure delivery systems.

Lymph flows under low pressure and depends on muscle movement and valves. Valves prevent backflow and support return to the bloodstream.

Different animal groups use body fluids for transport of nutrients, wastes, gases, hormones, or immune components. The exact composition and pathways vary.

Bloodstream infections can rapidly spread microbes or toxins systemically, leading to severe inflammation, shock, and organ dysfunction.

Cephalopods such as squid and octopus are active predators and have closed circulatory systems, supporting rapid oxygen delivery.

Innate defenses include antimicrobial molecules such as lysozyme and defensins. They act broadly against microbial structures.

Leukocyte numbers often rise during infection as the immune system responds to pathogens. Interpretation depends on species and condition.

Complete ventricular separation prevents mixing and supports efficient oxygen delivery, which is important for endothermy and sustained activity.

Arteries experience high pressure from ventricular contraction. Elastic walls stretch and recoil, helping maintain blood flow between heartbeats.

Complement proteins are part of innate immunity and can opsonize microbes, promote inflammation, and form membrane attack complexes.

Secretions such as tears and saliva contain antimicrobial substances and wash microbes from surfaces. These are innate barrier defenses.

Blood pressure results from cardiac pumping and resistance in blood vessels. It is regulated by heart rate, vessel diameter, blood volume, and hormones.