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Mastering biology Chapter 13 - Question 3 - Multiple Choice Homology is evidence of ________.

Fudgin [204]

Answer:

Homology is evidence Divergent Evolution

Explanation:

When we study DNA sequences from different species, we conclude that all the living organisms have been arise from a single common ancestor and due to homology between different species, it is also concluded that organisms now-a-days are a result of Divergent Evolution from a single common ancestor.

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3 years ago

What does it mean when pathogens are referred to as contagions?

Triss [41]

A pathogen is a disease carrying vector that has the ability to spread using a variety of different mechanisms. A pathogen that is a contagion has the ability to spread through touch. An example of such a pathogen would be the one that results in staph infections.

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3 years ago

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A. How do the Earth’s physical factors influence population density? When population growth increases in an area, what is happen

madreJ [45]

Question 1 The world's population is spread very unevenly. Some spaces are empty or very sparsely populated: we speak of human deserts:

• Cold polar environments are the least populated regions: the ground, frozen permanently, prevents any form of agriculture, the very low temperatures make the habitat difficult.

• The hot or cold desert environments are also not busy: the lack of rain and the strong heat during the day limit the activities of men. The only exceptions are oases.

• The role of relief is more difficult to define. High temperate mountains like the Alps are generally sparsely populated but tropical chains like the Andes have a high population density. However, men have generally settled in the plains, in the valleys (along with the rivers) and on the coasts.

There are also other factors unrelated to land factors that influence population density such as job availability, or even historical factors.

Question 2: Birth rate:

The birth rate (sometimes called the crude birth rate) is the ratio of the annual number of births to the average total population for that year. When the population grows, the contact between people will be more permanent, and it will increase the marriage rate, and thus the birth rate. Age structure:The age structure is a mode of graphical representation of the structure (of age as well as of sex) of a population which constitutes a synthetic image of the past, present and future of the population.When a population resides for a long time in the same place (in favorable conditions, not raising the death rate and without moving), this will vary the age structure by observing an increase in the elderly population.

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3 years ago

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Four types of compounds—carbohydrates, lipids, proteins, and nucleic acids—within living organisms

lisabon 2012 [21]

The 4 types of organic compounds and their subdivisions within living organisms are:
1. Carbohydrates:
- Monosaccharides,
- Oligosaccharides,
- Polysaccharides.
2. Lipids:
- Fats,
- Phospholipids,
- Waxes,
- Sterols.
3. Proteins:
- Primary structure (amino acid sequence),
- The secondary structure,
- The tertiary structure,
- The quaternary structure.
4. Nucleic acids:
- DNA (deoxyribonucleic acid),
- RNA (ibonucleic acid).

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3 years ago

Define monohybrid cross with explanation

UkoKoshka [18]

Answer: A monohybrid cross is a breeding experiment between P generation (parental generation) organisms that differ in a single given trait. The P generation organisms are homozygous for the given trait. However, each parent possesses different alleles for that particular trait. A Punnett square may be used to predict the possible genetic outcomes of a monohybrid cross based on probability. This type of genetic analysis can also be performed in a dihybrid cross, a genetic cross between parental generations that differ in two traits.

Traits are characteristics that are determined by discrete segments of DNA called genes. Individuals typically inherit two alleles for each gene. An allele is an alternate version of a gene that is inherited (one from each parent) during sexual reproduction. Male and female gametes, produced by meiosis, have a single allele for each trait. These alleles are randomly united at fertilization.

Explanation: The single trait being observed is pod color. The organisms in this monohybrid cross are true-breeding for pod color. True-breeding organisms have homozygous alleles for specific traits. In this cross, the allele for green pod color (G) is completely dominant over the recessive allele for yellow pod color (g). The genotype for the green pod plant is (GG), and the genotype for the yellow pod plant is (gg). Cross-pollination between the true-breeding homozygous dominant green pod plant and the true-breeding homozygous recessive yellow pod plant results in offspring with phenotypes of green pod color. All genotypes are (Gg). The offspring or F1 generation are all green because the dominant green pod color obscures the recessive yellow pod color in the heterozygous genotype.

Monohybrid Cross: F2 generation

Should the F1 generation be allowed to self-pollinate, the potential allele combinations will be different in the next generation (F2 generation). The F2 generation would have genotypes of (GG, Gg, and gg) and a genotypic ratio of 1:2:1. One-fourth of the F2 generation would be homozygous dominant (GG), one-half would be heterozygous (Gg), and one-fourth would be homozygous recessive (gg). The phenotypic ratio would be 3:1, with three-fourths having green pod color (GG and Gg) and one-fourth having yellow pod color (gg).

What Is a Test Cross? How can the genotype of an individual expressing a dominant trait be determined to be either heterozygous or homozygous if it is unknown? The answer is by performing a test cross. In this type of cross, an individual of unknown genotype is crossed with an individual that is homozygous recessive for a specific trait. The unknown genotype can be identified by analyzing the resulting phenotypes in the offspring. The predicted ratios observed in the offspring can be determined by using a Punnett square. If the unknown genotype is heterozygous, performing a cross with a homozygous recessive individual would result in a 1:1 ratio of the phenotypes in the offspring.

Using pod color from the earlier example, a genetic cross between a plant with recessive yellow pod color (gg) and a plant heterozygous for green pod color (Gg) produces both green and yellow offspring. Half are yellow (gg), and half are green (Gg). (Test Cross 1)

A genetic cross between a plant with recessive yellow pod color (gg) and a plant that is homozygous dominant for green pod color (GG) produces all green offspring with heterozygous genotype (Gg). (Test Cross 2)

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