Answer:
D. They define geological periods because scientists use them as reference points for tracking the history of the earth.
Explanation:
Catastrophic events related to changes in geological timeline are very useful in defining geological periods.
These events have very significant appearance in the geological record and can be used to determine the history of the earth.
The catastrophic events usually culminates into extinction cycles or termination of some organisms from the earth surface.
Geologists use these events that are often wide spread to delineate geological periods.
Answer:
The correct answer is C. Mammals can produce milk for their offspring.
Mammals are the members of class mammalia. The word mammalia was derived from Latin word "mamma" which means "breasts" as they had a unique feature i.e. presence of mammary glands.
These glands were evolved from a special types of sweat glands and became specialized in the production of milk, especially in females.
They help the mothers in providing nourishment to the offspring.
Other features of mammals may include four chambered heart, hair and fur, three middle ear bones, etc.
Explanation:
Answer:
Sow outdoors in late spring or start seed indoors about eight to 10 weeks before the last frost. Keep soil moist until the seed germinates. Mint seed germinates in 10 to 15 days. Seed-grown plants should reach harvestable size within two months.
The change of maximum heart rate (MHR) is the same from ages 20 to 26. At age 20, a person has an MHR of 200 bpm and at the age of 26, a person has an MHR of 194 bpm, there's a 4 bpm difference. While at the age of 40, a person has an MHR of 185 bpm and at the age of 46, a person has an MHR of 182 bpm, there's a difference 4 bpm. Therefore, the change in MHR for the same range (20-26) and (40-46) are the same.
Answer:
Mrs. Ritter, whose blood type is B (Bi) is right in claiming that Ian - blood type A (Ai)- is the father of her baby, with blood type O (ii). Ex-boyfriend AB (AB) cannot be the father.
Explanation:
The blood type, according to the ABO system, is determined by the presence or absence of surface antigens A and B. In addition, genotypes can be co-dominant, in the case of A, B and AB, heterozygous (Ai or Bi) and recessive, in the case of group O (ii)
- <em>
</em><u><em>Type A</em></u><em> contains the antigen A and its genotype can be AA or Ai.
</em>
- <u><em>Type B</em></u><em> contains the antigen B, whose genotype can be BB or Bi.
</em>
- <u><em>Type AB</em></u><em> contains both antigens and a single genotype expression AB.
</em>
- <u><em>Type O</em></u><em> blood lacks surface antigens, its genotypic expression being ii.</em>
According to this, to check if Mrs Ritter's baby is Ian's child, a crossing can be done:
♂ Ai
♀ Bi
Alleles A i
B AB Bi
i Ai ii
<u>Ian and Mrs Ritter have a 25% chance of having a child with blood type O (ii), so the baby may be Ian's child</u>.
To find out why the ex-boyfriend can't be the father
♂ AB
♀ Bi
Alleles A B
B AB BB
i Ai Bi
It is not possible that Mrs. Ritter's ex-boyfriend is the father of the baby, as the possible offspring in the crossover are A, B or AB.
