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KATRIN_1 [288]
3 years ago
5

A zebra mussel is discovered in a lake in Pennsylvania for the first time. Why would this make an ecologist worried?

Biology
1 answer:
Anna71 [15]3 years ago
3 0

If a zebra mussel is discovered in a lake in Pennsylvania, then the ecologist would be worried because it is an invasive species. The zebra mussel is native to Ukraine and Russia, but if it has been found in Pennsylvania, than it means that it has been introduced in this area. As an invasive species, the zebra mussel can be very dangerous for the native species in the lake. The invasive species usually are more competitive for food sources than the native species, manage to reproduce quicker, bring in diseases, and the native species tend to not have defense mechanisms for them. This leads to rapid decline or even extinction in the native species, while the invasive spreads out quickly and takes over, resulting in dramatic change in the whole ecosystem.

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Which continents contain coal fields that provide evidence for continental drift? Check all that apply.
Grace [21]

Answer:

Asia

Explanation:

could be south/north america not 100% sure

4 0
3 years ago
Resethelp 1. Structure describes the alpha-helices and beta-sheets that are formed by hydrogen bonding between backbone atoms lo
ss7ja [257]

1. Answer;

-secondary structure;

Explanation;

Protein secondary structure refers to regular, repeated patterns of folding of the protein backbone. The two most common folding patterns are the alpha helix and the beta sheet. In an alpha helix, the polypeptide backbone coils around an imaginary helix axis in clockwise direction. In the beta sheet secondary structure, the polypeptide backbone is nearly fully extended. The R-groups are alternately pointed above and then below the extended backbone.

2. Answer;

- Quaternary structure

Explanation;

-Many proteins are formed from more than one polypeptide chain. The Quaternary structure describes the way in which the different subunits are packed together to form the overall structure of the protein. For example, the human hemoglobin molecule shown below is made of four subunits.

3. Answer;

-Tertiary structure

Explanation;

Tertiary structure refers to the overall folding of the entire polypeptide chain into a specific 3D shape. The tertiary structure of enzymes is often a compact, globular shape.

The tertiary structure is the structure at which polypeptide chains become functional. At this level, every protein has a specific three-dimensional shape and presents functional groups on its outer surface, allowing it to interact with other molecules, and giving it its unique function.

4. Answer;

Primary structure

Explanation;

-It is the simplest level of protein structure and is simply a sequence of amino acids in a polypeptide chain. For example, the hormone insulin has two polypeptide chains, A and B. Each chain has its own set of amino acids, assembled in a particular order. For instance, the sequence of the A chain starts with glycine at the N-terminus and ends with asparagine at the C-terminus, and is different from the sequence of the B chain.

7 0
3 years ago
Which of the following is NOT a source of dissolved oxygen in the water?
lesantik [10]

Answer:

A. humans going underwater and exhaling

Explanation:

The dissolved oxygen in water refers to the amount of oxygen that is found in water. However, there are various ways that oxygen dissolves in a body of water, these includes;

- Photosynthesis of aquatic plants: Oxygen is the waste product of the photosynthetic process carried out by green plants. Hence, when aquatic plants undergo photosynthesis, oxygen from them tend to dissolve into water.

- Diffusion from the atmosphere: Oxygen from air or atmosphere also dissolves in water

- aeration as water moves over rocks and debris, and from wind and waves

However, humans do not exhale oxygen but carbon dioxide, hence, it is not a source of dissolved oxygen

4 0
3 years ago
What is the primary reason that species are overharvested?
son4ous [18]
<span>Market demand for goods associated with a species.</span>
7 0
3 years ago
There was ________ years between the heliocentric theory and geocentric theory
MaRussiya [10]

Answer:

The geocentric model held sway into the early modern age, but from the late 16th century onward, it was gradually superseded by the heliocentric model of Copernicus (1473-1543), Galileo (1564-1642), and Kepler (1571-1630). There was much resistance to the transition between these two theories.

Explanation:

8 0
3 years ago
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