Anatomy and Physiology MCQs

On which molecule is the energised cross-bridge which produces muscle cell contraction located?

Fibrin

Troponin

Actin

Myosin

The myosin molecule has a “cross-bridge”. The actin molecule has the binding site for the cross-bridge which is covered by tropomyosin. Ca binds to troponin in order to move tropomyosin away from the binding site.Energy for Muscle Contraction

Author: rikazzz Comment

Skeleton and Joints

One of the following lists contains only bones in the appendicular skeleton. Which one?

Patella, ethmoid, femur, coccyx, tibia

Clavicle, fibula, metatarsal, phalange, radius

Humerus, scapula, occipital, metacarpal, sternum

Ulna, radius, phalange, mandible, coxal

The coccyx, occipital, sternum and mandible are parts of the axial skeleton.

Author: rikazzz Comment

Cells and Tissues

The process of “diffusion” through a membrane may be described by which of the following?

The movement of ions and molecules away from regions where they are in high concentration towards regions where they are in lower concentration.

The use of energy from ATP to move ions and small molecules into regions where they are in lower concentration.

The plasma membrane engulfs the substance and moves it through the membrane.

The use of energy from ATP to move water molecules against their concentration gradient.

The choices with ATP are nonsense. While choice C refers to endocytosis.

Author: rikazzz Comment

Chemistry for Physiology

What is the difference between “molarity” and “osmolarity”?

Molarity applies only to covalent compounds, while osmolarity applies only to ionic compounds.

Osmolarity is molarity multiplied by two.

The molarity and osmolarity of a solution are the same for dissolved ionic compounds but are different for dissolved covalent compounds.

Osmolarity refers to the concentration of dissolved particles in a solution which may not be the same as the number of moles of substance that was dissolved per litre of solution.

Choice D is better than choice A as molarity can also be applied to ionic compounds.

Author: rikazzz Comment

Cells and Tissues

Which one of the following is NOT a function of membrane proteins?

They form a structure called a glycocalyx.

They attach cells to each other.

They form passageways to allow solutes to pass through the membrane.

They from receptors which can bind messenger molecules.

The glycocalyx is thought of as being membrane carbohydrates.

Author: rikazzz Comment

Cardiovascular System

Which structure has the thickest wall?