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Natalka [10]
1 year ago
13

Which statement best describes a keystone species?

Biology
2 answers:
worty [1.4K]1 year ago
8 0

The correct answer is option d. its absence would affect many organism present in the community.

The keystone species are the one, who play a very important role in the ecosystem. In case, the keystone species is wiped off from a particular ecosystem, then  the function of the ecosystem would cease and lead to a major effect. Hence, the keystone species is very important for the survival of ecosystem.

Tpy6a [65]1 year ago
4 0

The answer is D. The definition of keystone species is a species on which other species in an ecosystem largely depend, such that if it were removed, the ecosystem would change drastically.

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A scientist isolated the Hepatitis B surface protein gene and introduced it into the DNA of a banana plant. The scientist tested
omeli [17]

Answer:

A. The gene for surface protein was transcribed and translated.

Explanation:

Because all living organisms use the same genetic code, it is possible to express genes from one organism in the other. In this case, the DNA sequence that corresponds to the hepatitis B surface protein gene has been inserted into the banana, and the protein is expressed.

For the protein to be expressed, the gene must have been successfully transcribed into an mRNA by the banana plant machinery. This mRNA has then been translated into a protein that means the hepatitis B surface protein is now present in the cell.

4 0
2 years ago
A scientist notices that when she adds a small, water-soluble molecule to a dish of cells, the cells turn off transcription of a
Lelechka [254]

Answer:

Enzyme-linked

Explanation:

The cell surface receptors that have intracellular domains associated with enzymes are called enzyme-linked receptors. The added molecule was water-soluble and cannot pass through the membrane to bind to intracellular receptors. Binding of the added molecule to the enzyme-linked receptor led to the activation of associated enzymes to generate the response (down-regulation of expression of the target gene).

Examples of enzyme-linked receptors include tyrosine kinase receptors. Binding of the signaling molecule to these receptors triggers phosphorylation of the intracellular domain which in turn transmits the signal to the cytoplasmic messenger.

7 0
1 year ago
Why the location and quality of food sources in the soil are sometimes likely to stimulate random movements by C. Elegans, but a
Kipish [7]

Answer:

The Caenorhabditis elegans dauer state is a hibernation-like state of diapause that displays a dramatic reduction in spontaneous locomotion.

Explanation:

Mutations affecting the neurotransmitter dopamine, which regulates voluntary movement in many organisms, can stimulate movement in dauers. The movement of quiescent animals is stimulated by conditions that reduce dopamine signaling and also by conditions predicted to increase dopamine signaling.The stimulation of movement by increased dopamine is much more pronounced in quiescent daf-2(−) dauer and dauer-like adult animals.

In C. elegans hermaphrodites, dopamine is produced by eight neurons and signals via at least four dopamine receptors, DOP-1 through DOP-4. In addition, a presynaptic reuptake transporter, DAT-1, removes dopamine from the extracellular space to terminate signaling. In C. elegans, dopamine is best known for mediating the “basal slowing response” in which the animal's movement slows when it encounters food..  Dopamine is thought to be released in response to food and to act on motor neurons to modulate the animal's movement . Animals that cannot produce dopamine fail to slow in response to food and exogenous dopamine slows the movement of animals cultured without food.The response to dopamine in this situation is complex, as the absence of specific dopamine receptors can have either positive or negative effects on movement.

8 0
2 years ago
Ground squirrels are found in many areas of the United States. They live in underground burrows and are often attacked by birds
Ket [755]

The population of the ground squirrels will be limited by the population of the hawks. The population of the hawks, thus, will be a limiting factor for the population of the ground squirrels. The Hawks are the birds of prey that feeds on squirrels. With the increased number of hawks in the same area as them will put these squirrels in danger. The population of the tree squirrels, however, will have no affect on the population of the ground squirrels. The genetic variability and breeding season are not limiting factors for their population either.

Hence, the correct answer is 'option B - a population of hawks'.

4 0
2 years ago
Read 2 more answers
Which statement about DNA replication is FALSE?
Alexandra [31]

Answer:

C. DNA ligase adds nucleotides to the lagging strand

Explanation:

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5 0
2 years ago
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