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3 years ago

Dinosaurs disappeared from Earth 65,000,000 years ago. Express this number in scientific notation.

Biology

2 answers:

Nana76 [90]3 years ago

5 0

6.5 x 10^7

Move the decimal point 7 spaces to the left.

cestrela7 [59]3 years ago

4 0

6.5*10^7 is the answer.
six point five multiplied by ten to the seventh power.

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In watermelons, bitter fruit (B) is dominant over sweet fruit (b), and yellow spots (S) are dominant over no spots (s). The gene

NikAS [45]

Answer:

A) 9:3:3:1

B) All bitter fruit, yellow spotted offsprings

C) Phenotypes are bitter yellow spotted (4), bitter no spot (4), sweet yellow spot (4), and sweet no spot (4). 1:1:1:1

Explanation:

This is a typical dihybrid cross involving two genes, one coding for fruit taste and the other for spot color. The allele for bitter taste (B) and yellow spot (S) is dominant over the allele for sweet taste (b) and no spot (s) respectively.

Hence, a heterozygous F1 resulting from a cross between an homozygous dominant (bitter fruit, yellow spot) and homozygous recessive (sweet fruit, no spot) will have a BbSs genotype. The heterozygous F1 offsprings are self-crossed and produce gametes BS, Bs, bS, bs. (See punnet square). The F2 offsprings will have the following phenotypes: Bitter fruit, yellow spot (9)

Bitter fruit, no spot (3)

Sweet fruit, yellow spot (3)

Sweet fruit, no spot (1)

Back cross between a F1 offspring (BbSs) and homozygous dominant parent (BBSS) will produce all bitter fruit, yellow spot offsprings (see attached image). BBSS (4), BBSs (4), BbSS (4), and BbSs (4) are the offsprings' genotypes.

For the back cross between a F1 offspring (BbSs) and a homozygous recessive (bbss) parent, the Phenotypes with their proportions are as follows:

Bitter fruit, yellow spot (BbSs, 4)

Bitter fruit, no spot (Bbss, 4)

Sweet fruit, yellow spot (bbSs, 4)

Sweet fruit, no spot (bbss, 4).

4 0

3 years ago

How does DNA fold into a chromosome. What are the 6 steps

Xelga [282]

<span>The essential unit of DNA packaging is the nucleosome. A nucleosome consists of a small amount of DNA wrapped up with protein. The proteins that interact with DNA to form chromatin comprise a family of basic (positively charged) proteins called histones. There are five different types of histone protein: H1, H2A, H2B, H3, and H4. Of these, two molecules each of H2A, H2B, H3, and H4 combine to form a histone octamer. DNA wraps around the octamer, making 1 3/4 turns around the protein complex. The amount of DNA associated with the histone octamer is 146 bp. The octamer plus the DNA comprise what is called the nucleosome core. A small stretch of DNA (60 bp) runs between adjacent nucleosome cores, and is known as the linker. A single nucleosome consists of one core plus a linker. The total amount of DNA involved in a single nucleosome is approximately 206 bp. Chromatin therefore consists of DNA wrapped around one histone octamer after another, like a long string of beads.</span>

3 0

3 years ago

Name the condition characterized by attacks of difficult breathing and wheezing caused by spasms of the bronchial tubes.

Galina-37 [17]

Asthma is a condition which is characterized by attacks of difficult breathing and wheezing.

<span>It is a condition related to lung disease in which there is inflammation in bronchial tubes they become narrow, bronchial tubes are the passageway through which air enters and leave the lungs. So when it becomes narrow, it causes difficulty in breathing and sometimes it causes severe attacks.</span>

4 0

3 years ago

WHAT THREE KINGDOMS AROSE FROM PROTISTS ANCESTORS?

kati45 [8]

Plantae, Animalia, and Fungi
Hope this helps :)

3 0

3 years ago

After observing the F2 generation what conclusion did Mendel come to?

Aneli [31]

Answer:

The recessive trait reappeared about 25% of the time

Explanation:

There were no short plants in the F1 generation, although one of the parents was short. However, the characteristics reappeared in its original form in 1/4 of the F2 plants. He concluded that each hereditary characteristic is determined by two contrasting hereditary factors.

4 0

3 years ago