Primary succession occurs in essentially lifeless areas—regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier
Explanation:
Melanin is the pigment which absorbs UV light and it is present in skin and gives black colour to it.As we can see africans usually have black skin as they have to face direct uv light.
Answer:
Yeast cell structure
Each yeast cell has a distinct cell wall enclosing granular cytoplasm, within which can be seen a large vacoule and a nucleus (Fig. 214). The vacuole varies much in size according to the state of activity of the cell.
Yeast contains almost the same organelles of a mature eukaryotic cell. Nucleus, Golgi apparatus, mitochondria, endoplasmic reticulum, vacuole, and cytoskeleton are the most important one. Yeast cell particle size is typically of 5×10μm.
Explanation:
Yet, we don't always think of yeast as something remarkable. Instead, it's often perceived as plain or dull—a single-celled organism that, like a plant, lacks the ability to move on its own accord.
Answer:
The correct answer is - The neuron's intracellular charge must get more positive to meet a certain thresh hold in order to depolarize. If the neuron does not hit that threshold, then the neuron will not fire
Explanation:
In neuroscience, the depolarization of neurons shows the all or none law which is also called as all or nothing response. It states that all action potentials have the same size and the potential or strength of a nerve cell does not depend on the stimulus strength as all are the same size.
If a stimulus reaches a particular threshold cell or fiber will fire so either it will fire or not cross the threshold this is all or nothing response or law and depolarization is an example of it.
