How does light from stars indicate the universe is expanding?

As the hypothesis of sea-floor spreading predicts, the age of the ocean floor differs with location. What pattern does the ocean

zaharov [31]

Yes the hypothesis of the sea-floor spreads through the ocean ageing

7 0

3 years ago

Scientific explanations are accepted when

Stolb23 [73]

<u>ANSWER:</u>

Scientific explanations are accepted when there is sufficient evidence to prove them right. In addition, scientific explanations must be logical to be acceptable and must match as much evidences as possible.

<u>EXPLANATION:</u>

Scientific explanations explain something about the natural world by making use of observations and measurements.
These are usually tentative proposals that need to be verified or proved to be true.
The observations and measurements must prove the scientific explanation to be true or must support it so that it becomes acceptable.

3 0

3 years ago

Give two reasonsthat may account for the continuous firing of a<br> PostsynapticNeuron.

lyudmila [28]

Answer:

1.Continuous diffusion of negatively charged ions into the postsynaptic neurons , <u>which leads to continuous reversal of charges (hyperpolarization) and therefore continuous firing of action potential</u>

2. Inhibition of hydrolytic enzymes e.g (acetycholinesterase) that metabolize activities of cholinergic neurotransmitters e,g acetycholine at post synaptic cleft. leading to firing of action potential.

Explanation:

Neuron whose dendrites transmits action potential to the neuromuscular junction is called presynaptic neuron. While neuron that transmit action potential away from the neuronal synaptic junction, or from the neuromuscular junction to the cell body of adjacent neuron or to effectors (gland and muscles) are called post synaptic neuron.

The more negatively charged ions that diffused into the post synsptic neuron, the more depolarization, and the greater the frequency of action potential produced

The inhibition of activities of hydrolytic enzyme which metabolize cholinergic neurotransmitter leads to continuous excitatory activities of cholinergic neurotransmitters on the receptors at the postsynaptic neuron, and the more action potential

6 0

3 years ago

The cells of a mature pea plant have 10 chromosomes. How many chromosomes does a nucleus in the pea endosperm contain

Irina-Kira [14]

Answer:

15 chromosomes

Explanation:

The endosperm is formed through double fertilization where one male gamete nucleus with polar nuclei to form a triploid nucleus called the primary endosperm. The endosperm therefore will contain 15 chromosomes since the polar nuclei is diploid and the male gamete is haploid forming a triploid nucleus.

4 0

2 years ago

Select the correct answer from each drop-down menu. rna interference is a mechanism of eukaryotic gene regulation. in this mecha

rosijanka [135]

The dicer enzyme processes dsRNA and forms siRNAs, which suppress the expression of target genes by cutting mRNA. 1) siRNA 2) RNA.

<h3>What are siRNA fragments?</h3>

siRNA means small interfering RNA. This is a silencing RNA molecule involved in the RNA interference mechanism, intervening in the expression of a specific gene.

siRNAs are complementary double-stranded RNA molecules composed of about 20-21 nucleotides. siRNA originates from a long double-stranded RNA (dsRNA).

The dicer enzyme cuts dsRNA molecules and produces siRNA. siRNAs suppress the expression of target genes when cutting messenger RNA.

siRNAs suppress the expression of target genes by cutting the complementary messenger RNA (mRNA) into two halves. This is accomplished by the interaction of the siRNA with the RISC complex (RNA-induced silencing complex).

The two mRNA halves are later degraded by the cellular machinery, leading to the suppression of the gene expression.

siRNAs also participate in other pathways related to RNAi, such as in antiviral defense or in the chromatin structure organization.

RNA interference is a mechanism of eukaryotic gene regulation. In this mechanism, the enzyme dicer cuts dsRNA into smaller fragments called (1) siRNA, which form a complex with RISC and degrade specific (2) RNA.

You can learn more about siRNA at

brainly.com/question/7508257

#SPJ1

5 0

1 year ago