The scientific view's order of Earth's first living things to the most recent is described by choice C. cyanobacteria, hagfish, crocodilians, giant ground sloths. Cyanobacteria have lived on the Earth since the Precambrian supereon. Actually, they first appeared in the Archean eon (4-2.5 billion years ago). Hagfish, as other jawless fish, appeared in the Paleozoic era (541-252 million years ago). Crocodilians appeared in the Cretaceous period (145-66 million years ago). Giant ground sloths, also known as megatherium, appeared in the Pliocene epoch (5.33-2.58 million years ago).

6 0

3 years ago

A woman and a man are both heterozygous for a recessive allele for a rare genetic disease. If they have one child, what is the p

makkiz [27]

Answer:

If they have one child, the probability that he or she will be affected is 1/4.
If they have two children, the probability that at least one of them will be affected is 7/16.

Explanation:

A cross between two heterozygous Aa individuals will produce the followinf offspring: 1/4 AA, 2/4 Aa and 1/4 aa.

Since the disease is recessive, 1/4 of the offspring will have the aa genotype and 3/4 of the offspring will be unaffected.

Every time they have children new gametes were generated independently.

The probability of having no affected children both times is, according to rules of probability for independent events, 3/4 × 3/4 = 9/16 (it's the probability of having a healthy child the first time multiplied by the probability of having a healthy child the second time).

The probability of having at least one affected child is 1 - probability of no affected children = 1 - 9/16 = 7/16.

8 0

3 years ago