Top answers

All subjects
All levels

Describe the effect of calcium ions on tropomyosin and actin in skeletal muscle.

Within the muscle fibre tropomyosin is wrapped around actin filaments and it blocks the binding sites for the myosin-heads.

When calcium ion concentration increases, calciu...

AH
17387 Views

Describe the roles of DNA and RNA in determining the sequence of amino acids in proteins.

The sequence of bases (a gene) on DNA determines the order of amino acids that come together to form a polypeptide (protein) chain.

The DNA is 'unzipped' by enzymes called Helicases. This...

AH
4533 Views

People with AF often also have narrowing of the valve between the left atrium and the left ventricle. This causes the wall of the left atrium to become thicker. Suggest why.

With a narrowed (stenosed) AV valve it is more difficult (requires more pressure) for the blood to pass from atrium to ventricle. The blood pressure in the atria is increased.

This means ...

AH
3930 Views

Suggest why an artificial pacemaker can be used to treat AF.

An artificial pacemaker would generate regular electrical impulses in the atria.

The regular electical impulses from the pacemaker are stronger than the irregular impulses from the SAN, t...

AH
3933 Views

Suggest why people who have Atrial Fibrillation (AF) have an irregular pulse.

Atrial fibrillation (AF) is an abnormal condition of the heart.

In AF, irregular electrical impulses in the walls of the atria interrupt the normal regular impulses from the SAN.

...
AH
7112 Views

We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning