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3 years ago

The Paleozoic Era is the longest time period in the history of Earth.

Biology

2 answers:

never [62]3 years ago

5 0

Answer:

FALSE

Explanation:

The Paleozoic era is not the longest of all the era. It started from the Cambrian that was about 545 million years ago and ended in the Permian that was about 250 million years back.

The longest of all the era is the Precambrian era that started right from the time of formation of the earth that was the Hadean time and ended by the Proterozoic. The time range of this era was from 4.6 billion years to about 545 million years back.

Thus, the above given statement is false.

Rufina [12.5K]3 years ago

3 0

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Study this image of space. A cloud of gas and dust. What object is shown in this image? a nebula a red giant a supernova a neutr

zubka84 [21]

Answer: The image to be studied is missing from the question,so I attached it to my answer,please click on the attachment provided to view the image being studied.

The correct answer to the question is option A.

NEBULA

The object shown in the image is known as a nebula.

Explanation: A nebula is found in interstellar space,it has a form of a giant cloud of dust. When some stars goes into dying process,they explode throwing out gas and dust which forms a nebula.(a supernova remnants nebulae).

Some nebulae(singular form of nebula) are also found where new stars are being formed.

Nebula are the basic building blocks of the universe,they are made up 90% hydrogen,10% helium and other heavier elements in trace amounts from which stars and other solar systems are made.

Nebula exist in 5 distinct types namely;

Emission nebulae, Reflection nebulae,Dark nebulae, Planetary Nebulae and supernova remnants Nebulae.

4 0

3 years ago

A Tesla model 3 accelerates to the right at 26.8 m/s2. The Tesla has a mass of 1950 kg.

MArishka [77]

Answer:

Using the second Newton's law:

$force = m \times a \\ f = 1950 \times 26.8 = 52260$ N

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3 years ago

What is the determining factor for the transcription of structural genes of the trp operon?

padilas [110]

The right answer is 3. the availability of tryptophan in the environment

The TRP operon regulation depends on the availability of the tryptophan molecule (it depends if the cell need tryptophan or already has it).

There are two modes of regulation of the trp operon: Suppression and Mitigation

*Repression

The synthesis of operon mRNA is controlled by a repressor that blocks transcription when bound by tryptophan, which acts as a co-repressor.

The repressor, a 108 aa homodimer (ie 2 apo-repressor), has helix-turn-helix domains that interact with inverted repeats at the major groove of the operator, thus allowing its fixation.

In the absence of trp, the repressor is inactive and does not attach to the operator. The RNA polymerase can bind to the promoter and transcribe the trp E, D, C, B, A structural genes.

In the presence of trp, the repressor changes conformation and becomes active, so it binds to the operator, preventing RNA polymerase from accessing the promoter so transcription will not occur.

* The Attenuation

This is a premature termination of transcription that is a function of Trp concentration. It takes place at a late moment of transcription while regulation by repression is done during the initiation.

1st Case: Low Trp Rate, Continuous Transcription, → Formation of the Anti-attenuator in the absence of trp, and therefore the synthesis of tryptophan is continued.

2nd case: High rate of trp, stop transcription, → Formation of the attenuator in the presence of trp. This one will attenuate the synthesis of tryptophan.

4 0

3 years ago

A person can be tested for the allele that causes Huntington’s disease because the ___________________ of that allele is differe

lesya [120]

Hey friend.
Let's figure this out.
A person can be tested for the allele that causes Huntington’s disease because the "DNA SEQUENCE," of that allele is different from that of the normal allele.

Hope this helps. ;)

3 0

4 years ago

What is the meaning of selective premeable

Flura [38]

Answer:

Selective permeability is a property of cellular membranes that only allows certain molecules to enter or exit the cell. ... Movement across a selectively permeable membrane can occur actively or passively. For example, water molecules can move passively through small pores on the membrane.

Explanation:

8 0

3 years ago