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3 years ago

What are index fossils used to determine?

Biology

1 answer:

dlinn [17]3 years ago

8 0

Answer:

Index fossil that is also known as indicator fossil is used to determine the age of the layers of the rocks. It says that the new layer of sedimentary rocks lie over the old layer.

The deeper we go, the older the rocks we will find. Index fossil of animals that lived or survived only for a short period of time are very useful. An example of index fossil can be Ammonites that were found in Mesozoic era that was about 25-35 million years ago.

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The front leg of an iguana and the wing of a bird look different, but both limbs likely evolved from the same limb of a shared a

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Read 2 more answers

Fruit Flies, long wings (L) are dominat to short wings (l) show the results crossing a heterozygous with a long wing fly with a

GREYUIT [131]

Answer:

Fruit Flies, long wings (L) are dominant to short wings (l) show the results crossing a heterozygous with a long wing fly with a short wing fly What are the possible genotypes and phenotypes for this offspring?

Ll x Ll= LL, Li, Li and ii

2 homozygous (one is long wing fly and the other is short wing fly) and 2 dominant heterozygous

the genotype is 3:1 while the phenotype reflects 3 dominant long wing fly and 1 short wing fly

Explanation:

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3 years ago

There are six elements that make up 99.9% of the human body. which one is responsible for most of the material found in teeth?

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I believe that is calcium.

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2 years ago

Michelle was curious about her mother's blood type. Michelle knew that her own blood type was o,

babymother [125]

Blood type is determined by the I gene. IAIA and IAi determines A blood type. IBIB and IBi determines B blood type. ii determines 0 blood type. Michelle's mother must at least carry one recessive allele i.

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The blood type is determined by a gene, which is triallelic.

IA dominant over i. The person presents A type of antigens.

IB dominant over i. The person presents B type of antigens.

IA and IB are codominant. The person presents both types of antigens, A and B.

i is the recessive allele. The person does not present any antigen.

⇒ H0m0zyg0us dominant individuals IAIA, or heter0zyg0us Individuals IAi, will express the A blood type.

⇒ H0m0zyg0us dominant individuals IBIB, or heter0zyg0us Individuals IBi, will express the B blood type.

⇒ Individuals with h0m0zyg0us recessive genotype, ii will express the 0 blood type.

⇒ Individuals carrying IA and IB alleles will express the AB blood type.

To solve the problem, we will use this information.

We know that

Michelle is blood type 0

Father is blood type A

Brother and sister are blood type A

Mother??

⇒ If Michelle is blood type 0, then her genotype is ii. She must have received one recessive allele from her father and one from her mother.

⇒ This suggests that Michelle's father, who is blood type A, is heter0zyg0us IAi. He must have at least one dominant allele IA that determines his phenotype, and one i allele.

⇒ Michelle's brother and sisters are also type A. They might be either h0m0zyg0us dominant IAIA or heter0zyg0us IAi.

⇒ Michelle's mother should have at least one recessive allele i. She could be either IAi or IBi, or ii. There are three possible option for her genotype.

Let us make the Punnet squares to understand it better. We know the genotype of the father, but there are three options for the mother.

Option 1

Cross) father x mother

Parentals) IAi x IAi

Gametes) IA i IA i

Punnett square) IA i

IA IAIA IAi

i IAi ii

F1) 25% of the progeny is expected to be h0m0zyg0us dominant IAIA

50% of the progeny is expected to be heter0zygus IAi

25% of the progeny is expected to be h0m0zyg0us recessive ii

75% of the progeny is expected to be blood type A ⇒ IAIA and IAi ⇒ Sisters and brother

25% of the progeny is expected to be blood tye 0 ⇒ ii ⇒ Michelle

Option 2

Cross) father x mother

Parentals) IAi x IBi

Gametes) IA i IB i

Punnett square) IA i

IB IBIA IBi

i IAi ii

F1) 25% of the progeny is expected to be IAIB

25% of the progeny is expected to be heter0zygus IAi

25% of the progeny is expected to be heter0zygus IBi

25% of the progeny is expected to be h0m0zyg0us recessive ii

25% of the progeny is expected to be blood type AB ⇒ IAIB

25% of the progeny is expected to be blood type A ⇒ IAi ⇒ Sisters and brother

25% of the progeny is expected to be blood type B ⇒ IBi

25% of the progeny is expected to be blood tye 0 ⇒ ii ⇒ Michelle

Option 3

Cross) father x mother

Parentals) IAi x ii

Gametes) IA i i i

Punnett square) IA i

i IAi ii

F1) 50% of the progeny is expected to be heter0zygus IAi

25% of the progeny is expected to be h0m0zyg0us recessive ii

50% of the progeny is expected to be blood type A ⇒ IAi ⇒ Sisters and brother

50% of the progeny is expected to be blood tye 0 ⇒ ii ⇒ Michelle

Despite the fact we can not determine for sure the mother's genotype, we know that she carries at least one recessive allele, which is why Michelle's blood type is 0.

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2 years ago