Plz help I forgot my book at home only T or F

siniylev [52]

Blood dries over time. How quickly this happens depends on the surface on which the blood landed, how much blood the spatter contains, and the heat and humidity at the crime scene, but as a rule the outer edges of the stain dry first. Consequently, after the interior portion flakes off or is smeared by an object, a dry blood spatter can skeletonize, that is, leave behind a ring similar in appearance (if not color) to a water ring on a coffee table. Patterns of drying help analysts determine how long an assault went on, detect whether it took place all at once or in stages, and nail down possible crime scene contamination. Clotting patterns in blood provide similar information and can help nail down the time factor if analysts arrive at the scene before blood can dry. Clotting begins within 3 to 15 minutes, but actual times vary by amount, surface type and environment. Mixed levels of clotting can indicate that multiple blows or gunshots occurred over time

4 0

3 years ago

Read 2 more answers

The 1st organism in a food chain must always be what type of organism

mr_godi [17]

The 1st type is called autotrphs. Primary consumers are animals that eat primary producers; they are also called herbivores

5 0

3 years ago

(PLEASE HELP) Describe the difference between mechanical and electromagnetic waves. Give an example of each kind of wave related

Stolb23 [73]

One difference between mechanical and electromagnetic waves is that mechanical waves need a medium to pass through (solid, liquid, gas). EM waves can travel through matter or though a vacuum. In regards to telecommunications, EM waves can be radio waves, these are used in TV's, phones, computers, radios. Mechanical waves somewhat relate to this since radios produce sound;so an EM wave would turn into a mechanical vibration inside a speaker then sound would be produced.

5 0

3 years ago

Which of the following best explains how the expression of a eukaryotic gene encoding a protein wil differ if the gene is expres

Ivan

Answer: c. The protein will be made but will not function, because prokaryotes cannot remove introns.

Explanation:

Eukaryotic cells are cells that have membrane-surrounded organelles, such as a nucleus which is an organelle that stores the DNA, the genetic material. On the other hand, prokaryotic cells do not have a nucleus, and the genetic material is a single molecule, usually circular and closed and double-stranded, which is located in a sector of the cell known as the nucleoid (meaning "similar to the nucleus"), which does not imply the presence of a nuclear membrane.

<u>A gene is a unit of information at a DNA locus that codes for a protein. To synthesize that protein, DNA must be transcribed into messenger RNA (mRNA), and that mRNA is read by ribosomes in a process called translation or protein synthesis</u>. The difference between protein synthesis in prokaryotic and eukaryotic cells is that in prokaryotes, transcription and translation take place directly in the cytoplasm since there is no nucleus. In eukaryotes, transcription takes place inside the nucleus, to generate mRNA. This mRNA molecule is then directed to the cytoplasm where translation happens.

a. In prokaryotic cells, ribosomes are produced in the cytoplasm, whereas in eukaryotic cells they are generated in the nucleolus within the cell nucleus. So they both have ribosomes and they are used to make proteins, then this option is true.

b. RNA polymerase initiates transcription of all different types of RNA (mRNa, ribosomal RNA and transfer RNA). However, there are three RNA polymerase variations, each one translate a different type of gene. But, prokaryotic RNA polymerase can translate eukaryotic genes. Then this option is not true.

c. Prokaryotic cells don't have introns because those cells do not perform a post-transcriptional RNA modifications, only done by eukaryotic cells. One of the modifications is the excision of introns in RNA. An intron is a region of DNA that is part of the primary RNA transcript, but unlike exons, they are removed from the mature transcript prior to translation. <u>So, this remotion does not happen in prokaryotes because they just don't have introns</u>. Also, in prokaryotic cells. the translation and transcription machinery is coupled. So, the transcription and translation occurs simultaneously, there will be no remotion of introns then the protein will be synthesized differently, since the reading frame is changed. Remember that each codon (set of three nucleotides) codes for an amino acid. So if the gene sequence is different because certain sections of the gene have not been removed, the protein will be different, and probably it will not function. This option explains how the expression of an eukaryotic gene encoding a protein will differ if the gene is expressed in prokaryotic cells.

d. The genetic code is the set of rules that defines how a sequence of nucleotides in RNA is translated into a sequence of amino acids in a protein. This code is common to all living organisms, although there are small variations, and it has a unique origin and is universal. So, the code defines the relationship between each sequence of three nucleotides, called a codon, and each amino acid. The sequence of genetic material is composed of four distinct nitrogenous bases, which are represented by letters in the genetic code:

Adenine (A)
Thymine (T)
Guanine (G)
Cytosine (C)
Uracil (U), only in RNA (instead of T)

So, the genetic code is the same for eukaryotes and prokaryotes. So this option is not true.

7 0

3 years ago

The

I am Lyosha [343]

Answer:

valence electrons an element has in its outer shell, the easier it is to complete.

The most electron shells an element has, the easier it is to fill its outermost shell.

Explanation:

Non metals atoms bond to other elements by sharing or completing the valance electrons in other element. This is easily made when the other element lacks a small number of electrons, for example with Hydrogen it has 1 valance electron because of that it is easier to bond with other elements.

5 0

3 years ago