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Varvara68 [4.7K]
3 years ago
11

Fill in the blank with the correct sphere label. A: B: C:

Biology
1 answer:
miss Akunina [59]3 years ago
3 0

Answer:

A: geosphere

B: biosphere

C: hydrosphere

Explanation:

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38. What unites during fertilization?…………
Maru [420]

Answer:

B.The sperm and egg.

<h3>....Hope it helps you.....</h3>
4 0
2 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. <em>So, sparrows arrive in North America, mutated, and natural selection favored the beneficial mutations leading to a better adaptation to the environment.</em> 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. <em>This small population suffers low mutation, has not enough time to establish, and is more vulnerable to genetic drift events.</em> 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
Colostrum, which is rich in protein, micronutrients, and antibodies, is replaced by mature milk in about colostrum, which is ric
makkiz [27]
<span>Colostrum is replaced by transitional milk in about 2 to 4 days after birth. This milk contains high levels of lactose, fat, vitamins and more calories than the colostrum. Mature milk replaces the transitional milk and begins to appear near the end of the second week after childbirth. Mature milk contains more water than transitional milk.</span>
5 0
3 years ago
What is the greenhouse effect
Rasek [7]

Answer:

the trapping of the sun's warmth in a planet's lower atmosphere, due to the greater transparency of the atmosphere to visible radiation from the sun than to infrared radiation emitted from the planet's surface.

Explanation:

I think it can be incorrect also so refer to Science teacher also. also.

4 0
3 years ago
1. Why is the quadrat method useful for estimating snall populations? Explain why the same method would not be useful for counti
irga5000 [103]

Answer:

Quadrat method is used for estimating the number of individuals in an area. In this method, a large square area on the ground or water surface is marked, call it an enclave. The number of animals present in this enclave is counted. Then by assuming that the animals are less migratory and are uniformly distributed, their number for a large area is estimated by the use of unitary method of calculation. Example a 4 square feet area has 2 snails, then a 1000 square feet area will have (1000 x 2)/4, i.e, 500 snails in it. Fishes can be counted using this method only if they are confined in a small water body like a lake or a pond. Rivers are flowing so the fishes may move along its length which can give us an underestimate or an overestimate of their numbers. Sea has its depth and huge area, and fishes can be moving randomly in it. Hence this method will not work for river and sea fishes.

Explanation:

Hope this helps :D

7 0
2 years ago
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