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2 years ago

Which process helps make meiotic cells genetically different and occurs during prophase 1, but not during prophase II?

Biology

2 answers:

Sergeu [11.5K]2 years ago

8 0

Answer:

Crossing over

Explanation:

tresset_1 [31]2 years ago

6 0

Answer:

c. Crossing over

Explanation:

In meiosis, crossing over refers to the process where homologous chromosomes 'combine' with each other in order to exchange genetic material, which results in genetic variation. This process takes place during Prophase I of the first meiotic division.

Crossing over is extremely important for the variation - and survival - of a species, as it results in numerous genetic combinations that are passed from generation to generation.

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Why do viruses need hosts to reproduce

Olin [163]

When it comes into contact with a host cell, a virus can insert its genetic material into its host, literally taking over the host's functions. An infected cell produces more viral protein and genetic material instead of its usual products. Some viruses may remain dormant inside host cells for long periods, causing no obvious change in their host cells (a stage known as the lysogenic phase). But when a dormant virus is stimulated, it enters the lytic phase: new viruses are formed, self-assemble, and burst out of the host cell, killing the cell and going on to infect other cells. The diagram below at right shows a virus that attacks bacteria, known as the lambda bacteriophage, which measures roughly 200 nanometers

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2 years ago

The surface area of a plant's root system is substantially larger than the surface area of its shoot system. The extensive surfa

saveliy_v [14]

Answer:

Water and nutrient uptake.

Explanation:

The root system of a plant functions as conducting tissue for water and mineral nutrients that are essential for metabolic activities of the plant.

Extensive surface area of roots is an adaptation associated with efficient water and mineral nutrient uptake because this will increase the surface area of roots in contact with the soil.

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2 years ago

Most human genetic disorders are caused by the expression of_____

Reika [66]

D It all depends on dna, who, how, were, etc. Heredity

4 0

3 years ago

2. Dominant trait: cleft chin (C) Mother’s gametes: Cc

andre [41]

.2. Offspring Genotypes will be Cc or cc.

Offspring phenotypes : Cleft chin or no cleft chin.

% chance child will have cleft chin: 50%

3. % chance child will have arched feet: 25%

4. % chance child will have blonde hair: 50%

5. % chance child will have normal vision: 25%

Explanation:

CASE 1 :

Dominant trait: cleft chin (C)

Recessive trait: lacks cleft chin (c)

Father’s gametes: cc

Mother’s gametes: Cc

There are two possible combination of Gametes ,

C fom mother and c from father= Cc

c from mother and c from father = cc

Gametes of Cc Parents= $\frac{1}{2}C + \frac{1}{2} c$ ........(i)

Gametes of cc parents = $\frac{1}{2}c + \frac{1}{2}c$ .........(ii)

Combining (i) and (ii) we get,

$\frac{1}{2} Cc + \frac{1}{2} cc$

There fore offspring Genotypes will be Cc or cc

Offspring phenotypes :

Genotype Cc then phenotype= Cleft chin

Genotype cc then phenotype = Lacks cleft chin.

percentage chance child will have cleft chin = $\frac{0.5}{1}$ ×100

Therefore the chance is 50%.

CASE 2 :

Dominant trait: flat feet (A)

Recessive trait: arched feet (a)

Mother’s gametes: Heterozygous (Aa)

Father’s gametes: Heterozygous (Aa)

There are four possible combination of genotypes are =AA , Aa, Aa and aa

i.e. A from mother, A from father= AA

A from mother, a from father =Aa

a from mother, A from Father = Aa

a from mother, a from father = aa

Gametes of Aa parent = $\frac{1}{2} A + \frac{1}{2} a$

Gametes of other Aa parent = $\frac{1}{2} A + \frac{1}{2} a$

..................................................................................

$\frac{1}{4} AA + \frac{1}{4} Aa$

+ $\frac{1}{4} Aa$ + $\frac{1}{4} aa$

..........................................................................................

$\frac{1}{4}AA + \frac{1}{2}Aa +\frac{1}{4} aa$

Offspring Genotypes will be: AA or Aa or aa

Offsprings phenotype will be:

Genotype AA then phenotype will be Flat feet

Genotype Aa then phenotype will be flat feet

Genotype aa then Phenotype will be arched feet.

Percentage chance child will have arched feet = $\frac{0.25}{1}$ × 100 = 25%

CASE 3:

Dominant trait: Brown hair (B)

Recessive trait: Blonde hair (b)

Mother’s gametes: Homozygous recessive (bb)

Father’s gametes: Heterozygous (Bb)

This case is very similar to the case 1 as one parent is homozygous recessive and other parent is heterozygous.

Resulting in half Bb and halve bb combination.

Genotypes will be Bb or bb

Phenotypes will be :

Genotype Bb then phenotype Brown hair

Phenotype bb then Phenotype bb.

% chance child will have blonde hair: 50%

CASE 4:

Dominant trait: farsightedness (F)

Recessive trait: normal vision (f)

Mother’s gametes: Heterozygous (Ff)

Father’s gametes: Heterozygous (Ff)

This Case is similar to case 2

it will result in one-fourth FF , half Ff and one-fouth ff combination.

Therefore Genotypes will be: FF, Ff and ff

Phenotypes:

Genotype FF then phenotype farsightedness

Genotype Ff then phenotype farsightedness

Genotype ff then phenotype normal vision.

% chance child will have normal vision: 25%

3 0

2 years ago

Write about how the group of rock layers in record a forme include tilting erosion and folding

neonofarm [45]

Answer:

Most sedimentary rocks are formed in level layers. Therefore, the occurrence of tilted rock layers is evidence of mountain building. ... Tilting can also result when rocks are pushed upward, or uplifted. In some areas of the world, rock layers are so severely tilted that they may be bottom side up. Layered rocks form when particles settle from water or air. Steno's Law of Original Horizontality states that most sediments, when originally formed, were laid down horizontally. ... Rock layers are also called strata (the plural form of the Latin word stratum), and stratigraphy is the science of strata.

6 0

2 years ago