Question 1Easy
What are the thick filaments in muscle called?
- AMyosin
- BTropomyosin
- CActin
- DCollagen
Show answer and explanation
Correct answer: (A) Myosin
Explanation: Myosin makes up the thick filaments, whose heads form cross-bridges with actin.
Chapter 1 — Support and Movement in Living Organisms · Biology. These are 10 questions from the Magmo3 bank on this lesson, from easy to hard. Solve each one, then open "Show answer and explanation". Magmo3 has 40 questions on this lesson, each with an explanation.
What are the thick filaments in muscle called?
Correct answer: (A) Myosin
Explanation: Myosin makes up the thick filaments, whose heads form cross-bridges with actin.
The muscles found in the walls of internal organs such as the stomach and intestines are?
Correct answer: (C) Smooth muscles
Explanation: Smooth muscles are involuntary and are found in the walls of internal organs such as the stomach, intestines, and blood vessels.
The functional (contractile) unit of a muscle fiber is the?
Correct answer: (C) The sarcomere
Explanation: The sarcomere is the functional unit of contraction and lies between two Z lines.
Skeletal muscles differ from smooth muscles in that they are?
Correct answer: (B) Striated, voluntary, and multinucleate
Explanation: Skeletal muscles are striated, voluntary, and their cells are multinucleate, unlike smooth muscles which are involuntary and uninucleate.
A fish moves through water mainly using?
Correct answer: (A) Fins and body muscles
Explanation: A fish uses its fins along with the wave-like movement of its body muscles to swim through water.
According to the sliding filament theory, what happens during contraction?
Correct answer: (A) The actin filaments slide between the myosin filaments
Explanation: In the sliding filament theory, actin slides between myosin, shortening the sarcomere without any change in the length of the filaments themselves.
In the elbow joint, when the biceps (the flexor) contracts, what does the triceps do?
Correct answer: (D) It relaxes (extends)
Explanation: Muscles work in antagonistic pairs; when the flexor contracts, the extensor relaxes, and vice versa.
If we compare cardiac muscle with skeletal muscle, cardiac muscle differs in that it?
Correct answer: (D) Works involuntarily and does not tire
Explanation: Both are striated, but cardiac muscle is involuntary and works throughout life without tiring, unlike the voluntary skeletal muscle, which does tire.
Why do muscles work in antagonistic pairs?
Correct answer: (D) Because a muscle works only by contracting (pulling), not by pushing
Explanation: A muscle can only exert a pulling force when it contracts, so it needs another, antagonistic muscle to return the bone to its position.
If calcium is prevented from reaching the muscle fibers, what is expected to happen?
Correct answer: (C) Contraction does not occur (the muscle relaxes)
Explanation: Calcium is required to initiate contraction; without it, the myosin heads cannot bind to actin, so the muscle does not contract.
The first 10 questions in every subject are free, each with an explanation.