WHAT IS THE ANSWER????

Explain how the nucleus Observed in cheek cell

erastovalidia [21]

Answer:

The nucleus at the central part of the cheek cell contains DNA. When a drop of methylene blue is introduced, the nucleus is stained, which makes it stand out and be clearly seen under the microscope.

Copied

7 0

3 years ago

Read 2 more answers

Which main plant tissue is shown in green? dermal ground vascular meristem

Maksim231197 [3]

Ground tissue, which is also known as cortex, is the main plant tissue shown in green in the image.

8 0

2 years ago

Read 2 more answers

How is the energy of a nuclear reactor converted to electricity? The nuclear reactions produce electrical energy directly. Heat

timofeeve [1]

Nuclear power plants use the nuclear fission reaction to release energy and generate electricity through energy conversion. Take the pressurized water reactor nuclear power plant as an example to illustrate its working principle.

In the pressurized water reactor, a large amount of heat is generated by the self-sustaining chain fission reaction of the nuclear fuel nucleus. The coolant (also called the heat carrier) brings the heat in the reactor to the steam generator and transfers the heat to the working medium, water. The main circulation pump then delivers the coolant back to the reactor for recycling, thereby forming a circuit called the first circuit. This process is also the energy conversion process of nuclear fission energy converted into thermal energy.

The working medium on the secondary side of the U-tube outside the steam generator is vaporized by heat to form steam. The steam enters the steam turbine to expand work, and converts the heat energy released by the steam enthalpy into the mechanical energy of the rotor of the steam turbine. This process is called thermal energy conversion to mechanical energy. The energy conversion process. The steam that has done work is condensed into condensed water in the condenser and returned to the steam generator to form another circulation loop called the second loop. This process is called the energy conversion process of converting thermal energy into mechanical energy. The rotating rotor of the steam turbine directly drives the rotor of the generator to rotate, so that the generator emits electric energy, which is an energy conversion process that converts mechanical energy into electrical energy.

6 0

3 years ago

Which of the following is the correct meaning of transpiration?

Step2247 [10]

I think it's the evaporation of water through the stomata :)

3 0

3 years ago

Read 2 more answers

Consider a species of sparrow that originally lived only in Alaska but recently expanded its range through North America, then C

Shtirlitz [24]

Answer:

North America is the one with the highest heterozygosity frequency for most loci, followed by Central America, and finally, South America with the lowest heterozygosity level.

Explanation:

Some different forces or mechanisms might alter H-W equilibrium and lead to evolution, such as mutation, natural selection, migration, and genetic drift.

In the exposed example, we have a species of sparrow that migrates from Alaska to North America. Migration is unidirectional, which means that the movement occurs in only one direction: from Alaska to North America. We should also consider that the first immigrants colonized the area for the first time, meaning that there was not a receiving population of the same species already established. Finally, we need to consider that Alaska´s environmental conditions are very different from North America´s environmental conditions.

When a species arrives at a new place, it needs to adapt. The establishment and dispersion of the species in the new area depend on previous adaptation. So, when the firsts sparrow individuals arrived in North America, they faced new environmental conditions that acted as selective pressures that drove to the occurrence of mutations. A mutation implicates a stable and inheritable change in the genetic material. A mutation introduces changes, new alleles in the population, variability. But mutation rates are very low and have no evolutive direction, so they need another force to increase or decrease the mutant allelic frequencies. Natural selection benefits new advantageous alleles and transmits them to new generations changing their relative frequencies. So, sparrows arrive in North America, mutated, and natural selection favored the beneficial mutations leading to a better adaptation to the environment. This means that the heterozygosity level in this new recent population is very high.

As animals adapt to the new habitat and have better dispersal genes, they get to disperse even more. So they start new migration south, to Central America and South America. Again, they are moving to new regions with new conditions, and to establish they need to suffer new adaptations. But remember that we are talking about a recent event in time. Probably the animals migrating south are just a few. They have not spent enough time yet in the new area, to adapt to the new environment and to include new genes into their population. What is even more, as they are a small new population moving south, they are more vulnerable to genetic drift events. Genetic drift acts on a population decreasing the variability between individuals, hence, decreasing the heterozygosity. This small population suffers low mutation, has not enough time to establish, and is more vulnerable to genetic drift events. The heterozygosity level is probably inferior to North America´s one.

Comparing the three areas, we could say that North America is the one with the highest heterozygosity frequency, followed by Central America, and finally, South America with the lowest level of heterozygosity.

8 0

2 years ago