21. Which group of plants evolved first?

What is a control in an experiment

erastovalidia [21]

A control is used to establish a baseline in an experiment.

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3 years ago

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Do you think the shape of orchids is pure Mendelian inheritance, or is it more complex?

Mandarinka [93]

The genetic base of the shape of orchid is very complex.

Mendelian traits are described as simple traits determined by one gene. The different alleles of the gene contribute to the difference in the trait. This is true for some traits in plants, animals including humans and other organisms, but not for the shape of orchids.

The shape of orchid flowers is determined by the ABCDE group of genes that are responsible for the body plan in plants. These genes are the equivalent of HOX genes of animals.

The protein products of different genes of the ABCDE group interact with each other in complex ways creating different shapes of orchids.

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3 years ago

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PLEASE HELP

ANEK [815]

Answer:

Tubules?

Explanation

The trachea, spiracle, and air sac are part of their respiratory system, Howeber, the tubules are what take away the carbon dioxide from their system. Im not sure if they produce the carbon dioixde. But they are a part of what removes the carbon-dioxide from their body.

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3 years ago

Which type of mining is likely the least harmful to the environment? a. Surface mining b. Placer mining c. Subsurface mining d.

Roman55 [17]

There are different types of mining activities that depend on the extraction magnitude, the size and deepness of the mineral deposit, and its costs. The least harmful to the environment is Subsurface mining. Option C.

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There exist different types of mines depending on the extraction magnitude and methods.

The method used to extract minerals depends on the mineral deposit, the deposit size and deepness, and the work costs.

The environmental and health problems that mining activities produce involve the extraction process, transport of material, mineral processing, and the residues and wastes left at the extraction site that remain there for too much time and disperse to other areas polluting water, air, and soil.

Among the types of mines, the less destructive might be subsurface mining.

This type of mining has a less environmental impact because the disturbance caused on the land surface is minor than the impact caused by surface mines.

However, it still has harmful effects on the water and soil by contaminating them with acids and metals and intercepting aquifers.

Other forms of life are affected as well because of this pollution.

Workers are exposed to even more dangerous conditions.

Although subsurface mines have less permanent damage to the environment, they are still damaging and lack control policies.

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You can learn more about subsurface mine at

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3 years ago

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Which type of proteins can function as chemical messengers or as receptors in the plasma membrane? a. enzyme b. communication c.

maria [59]

The type of proteins that can function as the chemical messengers or as the receptors in the plasma membrane is a communication proteins; option A.

Proteins are large macromolecules composed of chains of amino acid units linked together by peptide bonds.

Proteins serve various functions such as:

communication

transport

defensive

enzyme

Communication of proteins such as the hormones can be function as the chemical messengers or as receptors in the plasma membrane.

Proteins are made up of hundreds or the thousands of the smaller units called as amino acids, which are attached to one another in the long chains. There are about 20 different types of amino acids that can be combined to make a protein.

To know more about protein visit:

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7 0

2 years ago