Answer:
3.9 billion years
Explanation:
The half-life of potassium-40 is the time it takes for half of it to decay.
After one half-life, half of the original amount will remain.
After a second half-life, half of that amount will remain, and so on.
We can construct a table as follows:
We see that the mass will drop to 10 g after three half-lives.
1 half-life = 1.3 billion years
3 half-lives = 3.9 billion years
What phenotypic ratio would you expect as a result of a test cross between a dihybrid organism and one that is homozygous recessive for alleles at two independent loci?
a. 3:1
b. 9:3:3:1
c. 1:1:1:1
d. 1:2:1
e. 9:4:2:1
Answer:
c. 1:1:1:1
Explanation:
When a heterozygous individual for two genes is test crossed with a double homozygous recessive individual, the progeny is obtained in 1:1:1:1 phenotypic ratio. This occurs as the heterozygous dominant individual forms four types of gametes in 1:1:1:1 ratio while the homozygous recessive individual would form only one type of gamete having one recessive allele for each gene.
For example, a test cross between TtRr (tall and red) and ttrr (short and white) would produce a progeny in following ratio=
1 tall, red: 1 tall, white: 1 short, red: 1 short, white
Here, T= tall, t= short, R= red, r= white
