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2 years ago

Which piece of evidence do scientists refer to back their idea that life-forms have changed (or evolved) over time?

Biology

1 answer:

Akimi4 [234]2 years ago

7 0

In older rock layers we find fossils of living things that no longer exist on earth.

Explanation:

Scientists often refer back to fossils found within sedimentary rocks to back their idea that life forms have changed over time.

Fossils are the preserved remains of organisms that once lived on earth. Special conditions must be in play before an organism can become a fossil like presence of hard parts.

Fossils are indicators of ancient life forms that has once lived.
They provide us with important clues to the nature of organisms that existed in time past.
Using phylogenetic relationship with their present day ancestors, it is possible to trace the evolutionary history of a specie.

Learn more:

Evolution brainly.com/question/6912833

Fossil brainly.com/question/12790206

#learnwithBrainly

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Carbohydrates and fats both

Daniel [21]

They are both digested in the intestine, if that if what you needed

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2 years ago

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the graph in figure 5.1 shows the growth of a bacterial population which of the following correctly describes the growth curve

defon

The right answer is exponential.

The bacterium multiplies by binary fission: the bacteria grow and then divide into two daughter cells separated by a septum of division formed by the cell wall. During division, the DNA is duplicated as well as the other constituents. Various enzymatic systems of synthesis and degradation participate in cell division.

Bacterial growth is the orderly growth of all components of the bacteria. It results in an increase in the number of bacteria.

During the growth, there is, on one hand, depletion of nutrients in the culture medium and, secondly, an enrichment of by-products of metabolism, potentially toxic. Growth can be studied in a liquid or solid medium.

1 - Growth curve: The growth of a bacterium is studied in a liquid medium. There are 6 phases which together constitute the growth curve.

. Latency phase: the zero growth rate (μ = 0). The duration of this phase depends on the age of the bacteria and the composition of the medium. This is the time required for the bacteria to synthesize the enzymes adapted to the new substrate (no lag phase if transplanting on the same medium as the previous one).

. Acceleration phase: There is an increase in the growth rate.

. Exponential growth: the growth rate reaches a maximum (μ = max). This phase lasts as long as the growth rate is constant. The doubling time of bacteria is the shortest. The cell mass is represented by viable cells (zero mortality).

. Slowing phase: the speed of growth decreases. There is a depletion of the culture medium and an accumulation of waste. There is a beginning of autolysis of bacteria.

. Stationary maximum phase: the growth rate becomes naked (μ = 0). Bacteria that multiply compensate for those that die.

. Decline phase: the growth rate is negative (μ <0). All the nutritional resources are exhausted. There is accumulation of toxic metabolites. There is a decrease in viable organisms and cell lysis under the action of endogenous proteolytic enzymes. However, growth persists by release of substances released during lysis (cryptic growth).

4 0

2 years ago

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Approximately how old is the earth?

Bas_tet [7]

I am pretty sure the answer is B. hope this helps and if it is wrong pls tell me thanks! :)

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2 years ago

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How are alleles for the same gene related? A. They have different genetic sequences but are found in the same location on a chro

Dmitrij [34]

Answer:

A. They have different genetic sequences but are found in the same location on a chromosome.

Explanation:

In genetics, alleles are the variant form of a gene. According to Mendel, there are usually two alleles for most genes except for few cases where there are multiple alleles. Each allele of a pair is contributed by each parent during sexual reproduction. For example, in a gene Tt, the alleles are T for tallness and t for shortness.

Alleles of the same gene are related in such a way that they have different genetic sequences but are found in the same location on a chromosome. The different genetic sequences makes them alternative form of each other.

5 0

2 years ago

fiasKO [112]

Explanation:

-Pheophytin

P680 the primary donor of Photosystem II becomes excited and transfers an electron to pheophytin. Pheophytin is the initial intermediate electron acceptor and carrier in Photosystem II; it is a chlorophyll-like molecule that lacks a central magnesium ion.

Further Explanation:

Photosynthesis is a chemical pathway that’s integral to producing energy in plants and other primary producers. Energy in the form of molecules of glucose is produced from light, water and carbon dioxide while oxygen is released. This occurs in several complex steps, photosynthesis is a rate limited reaction, depends on several factors including carbon dioxide concentration, ambient temperature and light intensity; the energy is retrieved from photons, I.e. particles of light, and water is used as a reducing agent. This occurs in the thykaloids, where pigment molecules like chlorophyll reside.

The chloroplast is a membrane bound organelle found in plants. It contains several invaginations of a plasma membrane called the thylakoid membrane. This contains chlorophyll pigments, in stacks called granum, while the internal spaces of the organelle are called the lumen. Liquid surrounds the granum, forming the stroma.

During the light reaction:

Light is absorbed by pigments in phosystem II (PSII). This energy is transferred among pigments til it gets to the reaction center, and is transferred to P680; this promotes an electron to a higher energy level where it then goes to an acceptor molecule, like Pheophytin .
Water supplies the chlorophyll in plant cell with replacement electrons for the ones removed from photosystem II. Additionally, water (H2O) split by light during photolysis into H+ and OH- acts as a source of oxygen along with functioning as a reducing agent.
the electron moves down an electron transport chain (to PS I)where it experiences continuous energy loss. This energy fuels the pumping of H+ from the stroma to thykaloid, leading to the formation of a gradient. The H+ move along their gradient and cross through ATP synthase, into the the stroma.
ATP synthase converts ADP and Pi to the energy storage molecule ATP.
The electron gets to photosystem I where it goes to pigments at P700. It absorbs light energy, the electron is promoted to a higher energy level, and passed to an electron acceptor. This leaves a space for another electron which is then replaced by one from photosystem II.
in the ETC, the molecule NADP is reduced to NADPH by providing H+ ions. NADP and NADPH are integral to the Calvin cycle where monosaccharides or sugars like glucose are produced after the modification of several molecules.