The atrioventricular valves.
Correct answer: B). With fewer contractions
The main function of a contractile vacuole is to maintain the sufficient amount of water in the protoplasm of the cell. For the freshwater amoeba contractile vacuole is needed to pump water and maintain a osmoregulation.
But when it is kept in sea water, more contraction is required to expel the water out of the cell in order to make the environment inside amoeba same as of sea water.
Answer:
Scientists usually use the potassium-argon method to date rocks that are older than about 1 million years. Uranium-238 is also used for radiometric dating. It has a half-life of 4.5 billion years. It decays to produce lead-206.
Answer:
Cross overs can lead to formation of chromosome pairs that have no mutant allele.
Explanation:
Cross overs can lead to formation of chromosome pairs that have no mutant allele.
For example -
Suppose "X" is a mutant allele and "x" is a mutant free allele.
Now when two homologous chromosomes contains a single mutant allele in different parts of the chromosome are crossed the following offspring are produced
X x
X XX Xx
x Xx xx
"xx" is a mutant free genotype.
Thus, crossing over can create a single mutation-free chromosome
