Answer:
C) primary cell wall --> plasma membrane --> cytoplasm --> tonoplast
Explanation:
When a potassium ion moves from the ground into a vacuole of a plant cell, it must pass through the different structures that are part of it.
First, the outermost layer of the cell is the cell wall. Plant cells may have a primary and a secondary wall, but the latter is not always present. The primary wall is always located outwards (and in the case of having a secondary wall, it will be located between the primary wall and the plasma membrane).
Then, inside the cell wall, we will find the plasma membrane (also called plasmalemma).
When crossing the membrane, the ion will be in the cytoplasm of the cell and will be directed towards the vacuole, which is surrounded by its membrane called tonoplast. The vacuole is an organelle that has no definite shape, although it is always surrounded by the tonoplast, and it contains different substances such as water and enzymes.
Answer:
The correct answer will be options
1. The position of the tropomyosin threads shift
2. Exposing myosin binding sites
3. Allowing the myosin head to attach to the actin filament
Explanation:
Calcium plays an important role in the contraction of muscles especially in the formation of the cross-bridge between myosin and actin filaments.
In the presence of calcium, myosin head binds the actin filament as calcium binds to the troponin which changes the configuration of the troponin which releases the tropomyosin from the myosin-binding site on actin.
Once the myosin binding site is freed, myosin binds the site and causes muscle contraction due to ATP hydrolysis.
Thus, the selected options are the correct answer.
