During stressful situations the ___ nervous system is activated.

Biology

1 answer:

antiseptic1488 [7]3 years ago

8 0

During stressful situations the sympathetic nervous system is activated <span />

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What are sources of electricity? List as many as you can. Where do people and other animals get energy to move around? Where do

DaniilM [7]

Answer:well it’s The Sun is the major source of energy for organisms and the ecosystems of which they are a part. Producers such as plants, algae, and cyanobacteria use the energy from sunlight to make organic matter from carbon dioxide and water. This establishes the beginning of energy flow through almost all food webs, and they are five main sources of energy - Solar energy from the sun - GEOTHERMAL-WIND - Biomass from plants - Hydropower from flowing water and from crystalline, the animals have sun has a main energy also from nutrients

Explanation:from scientifical viewing

4 0

3 years ago

How did Watson and Crick determine base pairing?

slega [8]

Watson and Crick determined base pairing by using Chargaff's rule to fit the bases together.

<h2>Further Explanation </h2>

Watson and Crick discovered that the DNA strands exists as a double helix, which appears like a twisted ladder.
In doing so, Watson and Crick used the Chargaff’s rule to confirm the base pairing in the double stranded DNA, so as to fit the complementary bases together.

<h3>Structure of DNA</h3>

DNA is a nucleic acid that carries genetic material in all living organisms. DNA is a double stranded nucleic acid whose building blocks are known as nucleotides.
Each nucleotide contains a sugar, a phosphate group and a nitrogenous base. The four nucleotide bases found in the DNA are Adenine, Cytosine, Thymine and Guanine.
The strands of DNA are attached to each other as a result of base pairing that occurs through hydrogen bonding as explained by Chargaff’s rule.

<h3>Chargaff’s rule. </h3>

Chargaff’s rule describes the base pairing in a DNA molecule, such that the base Guanine pairs with the base Cytosine in the complementary strand, while the base Adenine pairs with Thymine.
This means the number of thymine bases in a DNA molecule will be equal to the number of Adenine bases, while Guanine bases will be equal to Cytosine bases.
The result is a ratio of 1:1 between pyrimidines and purines in a molecule of DNA.

Chargaff's rule of base pairing provided Watson and Crick with a prove that their model was correct, since it agreed with Chargaff's as far as the percentages of A,T,G, and C in DNA are concerned.

According to Watson and Crick model, the hydrogen bonds could only form between adenine and thymine, and between cytosine and guanine to create an almost perfect fit.

Keywords; Watson and crick model, Chargaff’s rule, DNA, and base pairing.

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