Answer:
Options B, C, and D
Explanation:
The following assertions are accurate about the continental crust:
Its thickness ranges from 25 to 70 km.
It comprises various kinds of rocks.
This layer contains silicate minerals rich in sodium, potassium, aluminum, and calcium.
Answer:
C. They are carried by motor proteins using the cytoskeleton as a "roadway"
Explanation:
Vesicles hitch a ride on molecular motors such as kinesin or myosin, moving along the cytoskeleton until they reach their intended location, where they then fuse with the target membrane or organelle. Typically, vesicles progress from the ER to the cis Golgi, followed by movement from the cis to the medial Golgi, from the medial to the trans Golgi, and finally from the trans Golgi to the plasma membrane or other cellular compartments. While the predominant direction is forward, there are also vesicles that return from the Golgi to the ER, carrying proteins that should have remained in the ER (e.g., PDI) that were inadvertently enclosed in a vesicle.
Response: Option D.
Justification:
Active transport refers to how molecules or solutes travel through a membrane based on solute concentration differences.
This process is constant due to diffusion, which ensures ongoing movement of solutes across the membrane. Cells have reduced sodium (Na+) levels but increased potassium (K+) levels. Therefore, sodium's electrical and concentration gradients promote the ion's entry into the cell, assisted by the positive charge of Na+, which encourages inward movement to the negatively charged interior.
Thus, the right choice is D.
A muscle cramp happens when a muscle contracts involuntarily and suddenly. Various factors can cause this, such as insufficient minerals like calcium or poor blood flow.
By straightening and vigorously massaging an athlete's leg, the muscle relaxes and returns to its normal position.
