Answer:
The fossils in the lower layers are older than the fossils in the upper layers.
Explanation:
Answer is A
Firstly axon must reach the threshold level and then depolarisation occurs. Depolarisation phrase means sodium enters and potassium leaves the axon . Choice C can't be because main idea is the entering of sodium ions.
Answer:

Explanation:
As per the Newton's first law of motion,

where "v" is the final speed
"u" is the initial speed
"a" is the acceleration
and "t" is the time taken
Substituting the given values in above equation, we get -

The cart be traveling at a speed of
by the time it reaches level ground.
Answer:
(a) Gg × Gg; (b) genotypic = 1:2:1, phenotypic = 3:1
Explanation:
a) A cross between two gray seeded plants produces progeny with gray and white seeds in 3:1 ratio (302:98=3:1). This means that the parent plants are heterozygous and each has at least one recessive allele. If the allele "G" is responsible for gray seed and the allele "g" imparts white color to the seeds, the genotype of the heterozygous parents would be "Gg".
b) A cross between two heterozygous gray seeded parents would produce progeny in following ratio:
Genotype ratio= 1 GG: 2 Gg: 1 gg
Phenotype ratio= 3 Gray: 1 white