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boyakko [2]
2 years ago
9

Normal heart sounds are known as 'lub' and 'dub.' These sounds can be heart with a stethoscope as blood flows through the heart.

According to the model of the heart sound cycle, what most likely causes the sound known as 'lub'? A) The 'lub' sound is caused as the atrioventricular valves close. B) The 'lub' sound is caused as the atrioventricular valves open. C) The 'lub' sound is caused as the semilunar valves close. D) The 'lub' sound is caused as the semilunar valves open
Biology
1 answer:
BaLLatris [955]2 years ago
7 0

Answer: A) The 'lub' sound is caused as the atrioventricular valves close.

Explanation:

USATestprep just answered it

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Scientists studying hair samples can tell how long it has been since someone dyed or bleached their hair.
NISA [10]
False. It shows the DNA of someone.
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2 years ago
Density is mass per unit of volume. Which pair of lab instruments would a student use to measure the density of seawater?
9966 [12]
<h3>Answer:  C. a balance and a beaker</h3>

Explanation:

A balance would be used to measure the weight, which in turn effectively measures the mass (more or less). Imagine that we have a brick that we know is 1 pound. If we have an object that needs 5 bricks on one side to balance it out, then we know the object is 5 pounds.

The beaker is used to measure the volume. It's basically a measuring cup that you would find in the kitchen.

To get the density, you divide the mass over volume.

For example, if you have a material that has a mass of 100 grams and it's volume is 20 cm^3, then its density is 100/20 = 5 grams per cm^3.

7 0
2 years ago
Classify the following characteristics depending on if they describe events occurring in mitosis, meiosis I, or meiosis II.
Temka [501]

Answer:

Mitosis events are:

Results in 2 genetically identical

diploid nuclei

A diploid number of sister

chromatids align at the spindle

equator during metaphase

Meiosis I events are:

Results in 2 genetically diverse

haploid nuclei

Homologous chromosomes align

at the spindle equator during

metaphase

Homologous chromosomes pair

up during prophase

Crossing-over occurs during

synapsis

Meiosis II events are:

Results in 4 genetically diverse

haploid nuclei

A haploid number of homologous

chromosomes align at the spindle

equator during metaphase

Explanation:

Mitosis is a type of cell division which produces two daughter cells that are genetically identical to the parent cell. In mitosis, the chromosome number of the parent cell is maintained in the daughter cells i.e. a diploid cell (2n) will undergo mitosis to produce two diploid (2n) daughter cells. During mitotic division, sister chromatids (replicated chromosomes) are involved in the division stages. i.e. diploid sister chromatids align at the equator of the cell during Metaphase and also sister chromatids are separated or pulled apart to opposite poles during Anaphase.

Meiosis, on the other hand, is a kind of cell division that results in daughter cells with a reduced number of chromosome (by half). Since the chromosome number is reduced, meiosis occurs in a two step division process viz: Meiosis I and II.

Meiosis I produces two genetically different daughter cells. The daughter cells have a reduced number of chromosomes i.e. from diploid (2n) to haploid (n). Meiosis I involves homologous chromosomes (similar but non-identical chromosomes received from each parent) which pair up to form a TETRAD structure in the Prophase stage. This structure allows for an exchange of chromosomal segment between non-sister chromatids of homologous chromosomes, a process called CROSSING-OVER. Crossing-over is what makes the daughter cells genetically different from the parent cell. Homologous chromosomes also aligns at the equator of the cell during Metaphase and later separates during Anaphase.

Meiosis II divides the two daughter cells produced in meiosis I into four genetically different daughter cells. Since the chromosome number has been reduced from diploid (2n) to haploid (n) in meiosis I when homologous chromosomes separate, haploid sister chromatids are involved in the stages of meiosis II i.e. haploid sister chromatids align at the equator of the cell during Metaphase and eventually becomes pulled apart during Anaphase.

5 0
2 years ago
Unlike in prokaryotic cells, replication in eukaryotic cells
8_murik_8 [283]
<span>A. can start in many different places on a sequence at the same time. </span>
7 0
3 years ago
Read 2 more answers
How would cell division heal a broken arm
arsen [322]

Answer:

In order for a fracture to heal, the bones must be held in the correct position and protected. Soon after a fracture occurs, the body acts to protect the injured area, and forms a protective blood clot and callus around the fracture. New "threads" of bone cells start to grow on both sides of the fracture line.

Explanation:

6 0
2 years ago
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