The San Andreas Fault in California demonstrates earthquakes caused by

What is it about the life-cycle that makes cane toad populations successful?

Svetllana [295]

Cane Toads are very strong and adaptable, they are also poisonous throughout its life cycle, which is why they only have a few predators and have a life span of 10-15 years. Cane toads have poison glands, and the tadpoles are extremely toxic to most animals if consumed. They are productive breeders, they only need a small pool of water of almost any nature. The female cane toads can lay 8,000 to 35,000 eggs at a time and may produce two clutches in one year. The eggs will hatch within 24-72 hours and the tadpole stage may last from three to twenty weeks. Cane toads in the tropics grow really quick and may be sexually mature only within one year. Cane toads have been introduced to many regions of the Pacific and the Caribbean islands as a method of agricultural pest control because of their ravenous appetite, however, they are now considered pests and are dangerous to humans and animals, both wild and domesticated especially to dogs.

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3 years ago

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What evidence shows that biological molecules on earth form naturally?

Anestetic [448]

Explanation:

La siguiente entrada tiene como objetivo realizar una breve explicación sobre las moléculas biológicas lipídos y carbohidratos, las cuales son muy diversas ya que están formadas por carbono, lo cual hace que puedan formar muchos tipos de enlaces. Esta capacidad permite que las moléculas orgánicas adopten muchas formas complejas, como son las cadenas, las ramificaciones y los anillos.

Las moléculas biológicas son grandes polímeros que sintetizas para poder enlazarse con otras subunidades mucho mas pequeñas conocidos como monómeros. Las cadenas de subunidades estan unidas por enlaces covalentes los cuales se forman por deshidratación, estas cadenas pueden romperse por hidrólisis. La moléculas biologicas más importantes son los carbohidratos, lípidos, proteínas y ácidos nucleicos.

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3 years ago

What types of organisms produce sexually

Over [174]

A more stringent definition is agamogenesis which is reproduction without the fusion of gametes<span>. Asexual reproduction is the primary form of reproduction for single-celled organisms such as the </span>archaebacteria<span>, eubacteria, and protists. Many plants and fungi reproduce asexually as well.</span>

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3 years ago

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A DNA fragment is introduced into the lacZ gene of a plasmid, which also contains an ampicillin resistance gene. What is the app

zhenek [66]

Answer: The bacteria transformed with this particular plasmid will form white colonies on the plates containing ampicillin and Xgal.

Explanation: The lacZ gene produces an enzyme called β-galactosidase which is responsible for the breakdown of lactose into glucose and galactose. The lacZ gene is one of the three genes (the other two being lacA and lacY) of the lac operon which is responsible for the transport and mechanism of lactose in E. coli and many other bacteria.

In recombinant DNA technology, when a plasmid is to be used to transform a host cell, such markers are used to help screen the transformed cells from the ones that have not taken up the plasmid. Xgal present in the plates is an artificial substrate which is hydrolyzed by

β-galactosidase into 5-bromo-4-chloro-indoxyl which will dimerize and oxidise into 5,5'-dibromo-4,4'dichloro-indigo. This is a blue pigment which will give blue color to the bacterial cells. Introducing a DNA fragment in this lacZ gene will make it non-functional so it will not be able to produce the enzyme.

Therefore, when a bacterial cell is transformed with a plasmid containing ampicillin resistance gene and a DNA fragment introduced in the lacZ gene and then grown on plates containing ampicillin and Xgal, white colored colonies will appear. The white colonies will show the bacterial cells that have successfully taken up the plasmid with the DNA fragment incorporated in the lacZ gene as this will render the gene non-functional and will not produce β-galactosidase which will breakdown Xgal to give blue colonies. Since the plates contain ampicillin, only the bacterial cells that have been successfully transformed with the plasmid ( the ones that have the DNA fragment and the ones without it) will grow as the ampicillin resistance will give them resistance against ampicillin in the plates. The bacterial cells that have not taken up the plasmid will not be resistant to ampicillin and will not form colonies on the plate.

This is called blue-white screening which is used to identify successfully transformed host cells. A picture of this is given in the attachment, taken from the following website:

https://www.mun.ca/biology/scarr/Blue_&_White_Colonies.html

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3 years ago

In addition to providing food why are plants important to human society give three examples

TEA [102]

They produce oxygen they are used as shelter, they are used for blocking the shade, they sustain other animals that sustain the planet and us.

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3 years ago