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3 years ago

In which specimen were cells first identified

2 answers:

6 0

The appropriate response is a cork. The cell was first found and named by Robert Hooke in 1665. He commented that it looked peculiarly like cells or little rooms which friars occupied, in this way determining the name. However what Hooke really observed was the dead cell dividers of plant cells (cork) as it showed up under the magnifying lens.

Juliette [100K]3 years ago

4 0

Cells were first identified by Robert Hooke in cork, in the year 1665. He said that they looked quite similar to the cellula, contaned in the compartments. But, actually, they were dead cells of the cork. He used a microscope to observe these cells.

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Alleles can be described as 1. dominant 11. recessive III. codominant IV. partially dominant V. incompletely dominant O A. I, II

joja [24]

Answer:

A. I, II, III, and V only

Explanation:

In genetics, an allele refers to the specific form of a gene, which encodes traits. These alleles are usually in pairs in a diploid organism i.e. an organism with two sets of chromosomes. According to Gregor Mendel,

- An allele can either be DOMINANT when the allele masks the phenotypic expression of its allelic pair while the allele that is masked is said to be RECESSIVE.

- Two alleles can also be CO-DOMINANT when the two alleles are neither dominant or recessive over one another but are simultaneously expressed in that particular gene.

- Alleles can also be INCOMPLETELY DOMINANT when one allele is not completely dominant over the other, hence, forms a third intermediate phenotype when in combination with the second allele i.e. in an heterozygous state.

Based on this, an allele can be dominant (I), recessive (II), codominant (III), and incompletely dominant (V).

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3 years ago

_________________________ are the most reflective substances on the surface of Earth.

solniwko [45]

Answer:

The answer is snow

5 0

2 years ago

Read 2 more answers

Deltas are formed by the accumulation of

Natali5045456 [20]

A river delta forms by the deposition of sediments from the river when it slows to join a larger body of water.

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3 years ago

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Describe how blood is pumped and circulated through the body. Include the roles of the various chambers of the heart, the major

Korvikt [17]

The heart is a pump, usually beating about 60 to 100 times per minute. With each heartbeat, the heart sends blood throughout our bodies, carrying oxygen to every cell. After delivering the oxygen, the blood returns to the heart. The heart then sends the blood to the lungs to pick up more oxygen. This cycle repeats over and over again.

The circulatory system is made up of blood vessels that carry blood away from and towards the heart. Arteries carry blood away from the heart and veins carry blood back to the heart.

The circulatory system carries oxygen, nutrients, and hormones to cells, and removes waste products, like carbon dioxide. These roadways travel in one direction only, to keep things going where they should.

The heart has four chambers — two on top and two on bottom:

The two bottom chambers are the right ventricle and the left ventricle. These pump blood out of the heart. A wall called the interventricular septum is between the two ventricles.

The two top chambers are the right atrium and the left atrium. They receive the blood entering the heart. A wall called the interatrial septum is between the atria.

The atria are separated from the ventricles by the atrioventricular valves:

The tricuspid valve separates the right atrium from the right ventricle.

The mitral valve separates the left atrium from the left ventricle.

Two valves also separate the ventricles from the large blood vessels that carry blood leaving the heart:

The pulmonic valve is between the right ventricle and the pulmonary artery, which carries blood to the lungs.

The aortic valve is between the left ventricle and the aorta, which carries blood to the body.

What Are the Parts of the Circulatory System?

Two pathways come from the heart:

The pulmonary circulation is a short loop from the heart to the lungs and back again.

The systemic circulation carries blood from the heart to all the other parts of the body and back again.

In pulmonary circulation:

The pulmonary artery is a big artery that comes from the heart. It splits into two main branches, and brings blood from the heart to the lungs. At the lungs, the blood picks up oxygen and drops off carbon dioxide. The blood then returns to the heart through the pulmonary veins.

In systemic circulation:

Next, blood that returns to the heart has picked up lots of oxygen from the lungs. So it can now go out to the body. The aorta is a big artery that leaves the heart carrying this oxygenated blood. Branches off of the aorta send blood to the muscles of the heart itself, as well as all other parts of the body. Like a tree, the branches gets smaller and smaller as they get farther from the aorta.

At each body part, a network of tiny blood vessels called capillaries connects the very small artery branches to very small veins. The capillaries have very thin walls, and through them, nutrients and oxygen are delivered to the cells. Waste products are brought into the capillaries.

Capillaries then lead into small veins. Small veins lead to larger and larger veins as the blood approaches the heart. Valves in the veins keep blood flowing in the correct direction. Two large veins that lead into the heart are the superior vena cava and inferior vena cava. (The terms superior and inferior don't mean that one vein is better than the other, but that they're located above and below the heart.)

Once the blood is back in the heart, it needs to re-enter the pulmonary circulation and go back to the lungs to drop off the carbon dioxide and pick up more oxygen.

How Does the Heart Beat?

The heart gets messages from the body that tell it when to pump more or less blood depending on a person's needs. For example, when you're sleeping, it pumps just enough to provide for the lower amounts of oxygen needed by your body at rest. But when you're exercising, the heart pumps faster so that your muscles get more oxygen and can work harder.

How the heart beats is controlled by a system of electrical signals in the heart. The sinus (or sinoatrial) node is a small area of tissue in the wall of the right atrium. It sends out an electrical signal to start the contracting (pumping) of the heart muscle. This node is called the pacemaker of the heart because it sets the rate of the heartbeat and causes the rest of the heart to contract in its rhythm.

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3 years ago

The molecule that carries a great deal of chemical energy in its chemical bonds and is made in both photosynthesis and cellular

Mamont248 [21]

The answer is glucose

8 0

2 years ago