C. The Bering Land Bridge once connected what would be Russia and North America but the the movement of these continents separated the land bridge
In protista kingdom the organisms are represented in cartoon classified
Answer:
The correct answer is b. must be present in a population before natural selection can act upon the population
Explanation:
Genetic variation can be caused by mutation, recombination between chromosomes during meiosis and by fusion of two genetically different gametes during sexual reproduction.
This genetic variation is necessary for the evolution of any population. Natural selection acts on every individual and it decreases the frequency of those alleles that are not suited for the environment and increase the frequency of those alleles which helps the individual to survive in the changing environment.
Therefore genetic variation must be present in the population before natural selection act on the.
Answer:
<h2>B) 4, 6, 7, 1, 2, 3, 5</h2>
Explanation:
Action potential ,the change in electrical potential associated with the passage of an impulse along the membrane of exciting cell. The order of steps in generation of action potential is-4.A graded depolarization brings an area of an excitable membrane to threshold.→ 6. in excitable membrane ,after that, Sodium channel get activated,→ 7. aftre that Sodium ions enter the cell and depolarization occurs,→1.after that, then Sodium channels are inactivated,→ 2. Voltage-gated potassium channels open and potassium moves out of the cell, initiating repolarization, →3. Sodium channels regain their normal properties,→ 5A temporary hyperpolarization occurs.
DNA polymerase III has a subunit for proofreading during DNA replication. As replication continues and
the polymerase III enzyme detects a mismatched base pair, through a deformity in the double helix structure, the
polymerase backs up, nicks the mismatched base and replaces it with the correct
base before continuing replication.
