Ronald observes a sparrow's nest in a shrub outside his home. The table below describes his findings.
Week
Observations
1
Six eggs were laid in the nest.
3
Five eggs hatched, and one egg did not hatch.
One of the chicks disappeared.
7
Three of the chicks learned to fly, and another one disappeared.
What part of natural selection did Ronald observe?
adaptation
overproduction
selection
variation

Answer: Explanation:

Sickle hemoglobin differs from normal hemoglobin by a single amino acid: valine replaces glutamate at position 6 on the surface of the beta chain. Therefore the red blood cell bends differently giving it a sickle shape

Answer:

Explanation:

Sickle cell disease is a group of disorders that affects hemoglobin, the molecule in red blood cells that delivers oxygen to cells throughout the body. People with this disease have atypical hemoglobin molecules called hemoglobin S, which can distort red blood cells into a sickle, or crescent, shape.

Signs and symptoms of sickle cell disease usually begin in early childhood. Characteristic features of this disorder include a low number of red blood cells (anemia), repeated infections, and periodic episodes of pain. The severity of symptoms varies from person to person. Some people have mild symptoms, while others are frequently hospitalized for more serious complications.

The signs and symptoms of sickle cell disease are caused by the sickling of red blood cells. When red blood cells sickle, they break down prematurely, which can lead to anemia. Anemia can cause shortness of breath, fatigue, and delayed growth and development in children. The rapid breakdown of red blood cells may also cause yellowing of the eyes and skin, which are signs of jaundice. Painful episodes can occur when sickled red blood cells, which are stiff and inflexible, get stuck in small blood vessels. These episodes deprive tissues and organs, such as the lungs, kidneys, spleen, and brain, of oxygen-rich blood and can lead to organ damage. A particularly serious complication of sickle cell disease is high blood pressure in the blood vessels that supply the lungs (pulmonary hypertension), which can lead to heart failure. Pulmonary hypertension occurs in about 10 percent of adults with sickle cell disease.

Answer:B

Explanation:Earth’s core that cause the molten rock in the mantle layer to move, and it moves in a pattern.

Answer:

The Paleozoic is divided into six periods: the Cambrian, Ordovician, Silurian, Devonian, Carboniferous (in the U.S., this is divided into the Mississippian and Pennsylvanian Periods), and Permian. Most of these names derive from locations where rocks of these ages were first studied.

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Answer:

d

Explanation:

Answer:

the body has levels of organization that build on each other.Cells make up tissues,tissues make up organs,and organs make up organs system.

Answer:

Specialized systems are necessary in large multicellular organisms since 1. there is a division of labor between cells, 2. many individual cells cannot work together without coordination, and 3. most of the cells are not in direct contact with the outside environment

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Specialized systems are necessary in large multicellular organisms since 1. there is a division of labor between cells, 2. many individual cells cannot work together without coordination, and 3. most of the cells are not in direct contact with the outside environment.

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Answer:

Scientists began to mark division on the geologic time scale when patterns and similarities started emerging from archeological studies. Patterns such as the discovery of fossils that were formed within the same period.

Explanation:

Geologists who study matter that make up the Earth's crust (whether solid gaseous or liquid), as well as matter from other terrestrial planets and the processes that influence the formation and condition of this matter, are called geologists.

They have successfully calibrated history into various phases of time intervals. These intervals are event-based intervals. For example, you have Eons, Eras, and Periods.

An Eon is a billion years. An example is the Neoproterozoid Eon. Eons are made up of several Eras and Eras are made up of periods. An example of an era is the Mesozoic era. Whilst periods are smaller units of an era, eg. Triassic era.

As scientists deduced the causes for the formation of fossils and topographical remains/patterns, they collected events that occurred within the same time period and group them together.

This range of events became known as the geological time scale.

The age of fossils and rocks is also used to map out the calibrations on the scale.

The age of fossils and rocks is determined using the process of radioactive dating.

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Answer:

Population size is influenced by the per capita population growth rate, which is the rate at which the population size changes per individual in the population. This growth rate is determined by the birth, death, emigration, and migration. Pretty much Birth rate or Death rate.

Explanation:

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Answer:

LEARNING OBJECTIVES

Identify important checkpoints in cell division

Explain how errors in cell division are related to cancer

The length of the cell cycle is highly variable, even within the cells of a single organism. In humans, the frequency of cell turnover ranges from a few hours in early embryonic development, to an average of two to five days for epithelial cells, and to an entire human lifetime spent in G0 by specialized cells, such as cortical neurons or cardiac muscle cells. There is also variation in the time that a cell spends in each phase of the cell cycle. When fast-dividing mammalian cells are grown in culture (outside the body under optimal growing conditions), the length of the cycle is about 24 hours. In rapidly dividing human cells with a 24-hour cell cycle, the G1 phase lasts approximately nine hours, the S phase lasts 10 hours, the G2 phase lasts about four and one-half hours, and the M phase lasts approximately one-half hour. In early embryos of fruit flies, the cell cycle is completed in about eight minutes. The timing of events in the cell cycle is controlled by mechanisms that are both internal and external to the cell.

Explanation:

Regulation of the Cell Cycle by External Events

Both the initiation and inhibition of cell division are triggered by events external to the cell when it is about to begin the replication process. An event may be as simple as the death of a nearby cell or as sweeping as the release of growth-promoting hormones, such as human growth hormone (HGH). A lack of HGH can inhibit cell division, resulting in dwarfism, whereas too much HGH can result in gigantism. Crowding of cells can also inhibit cell division. Another factor that can initiate cell division is the size of the cell; as a cell grows, it becomes inefficient due to its decreasing surface-to-volume ratio. The solution to this problem is to divide.

Whatever the source of the message, the cell receives the signal, and a series of events within the cell allows it to proceed into interphase. Moving forward from this initiation point, every parameter required during each cell cycle phase must be met or the cycle cannot progress.

Regulation at Internal Checkpoints

It is essential that the daughter cells produced be exact duplicates of the parent cell. Mistakes in the duplication or distribution of the chromosomes lead to mutations that may be passed forward to every new cell produced from an abnormal cell. To prevent a compromised cell from continuing to divide, there are internal control mechanisms that operate at three main cell cycle checkpoints. A checkpoint is one of several points in the eukaryotic cell cycle at which the progression of a cell to the next stage in the cycle can be halted until conditions are favorable. These checkpoints occur near the end of G1, at the G2/M transition, and during metaphase

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Answer:

1. By refrigerating it(You can also add salt cuz salt acts as a preservative)

2. I have no clue

3. Biodegradable is a characteristic of an object which can decompose by the nature itself

4. Seven

5. Uhhmmm?

6. Both are necessary for a healthy diet (Also you haven't mentioned which meat) Meat like fish are good but mutton or chicken's meat are not specifically bad but you should try reduce the amount you eat

7. Kinda explained that in 6.

8. Population of eagles??????? It could reduce the population of birds but not really though. Well you mi6say birds live on trees but at the same time birds are not trees, the could just go to a far away place where human habitat is low or just migrate away

9. Yes it would be good. smoking does not only ruin the person who is smoking but also the people nearby.

10. Do it yourself

the age of the star because just like people as they grow older they become weak and so arr the stars their brilliance fade when they become older.

Answer:

It's the closest

Explanation:

I'm not sure but I think its correct :) hope this helps

Answer:

A 2008 study suggests that sympatric speciation has occurred in Tennessee cave salamanders.

Explanation:

Hope this helps

Answer:

3. fungus

4. tall grass

5. food is mostly animal

Answer:

I hope you understand please give brainliest

Explanation:

Newton's second law of motion can be formally stated as follows: The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.

Answer:

Yes it is written that second law of Newton is motion of an object

The smallest unit into which a substance can be divided without changing its chemical nature

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Answer:

a group of  atoms that form the smallest identifiable unit

Explanation:

Answer:

Aspirin tablets. Sponges. ...

Sponges made from trees. Chewing Gum. ...

Sapodilla tree. Carnauba Wax. ...

Copernicia prunifera. Henna Dye. ...

Henna tattoo. Rubber. ...

Tapping into trees for rubber.

Answer:

Rubber, sponges

Explanation:

these are Frome trees

Answer:

ddff  and DDFf

Explanation:

From the information given:

Let DD represents the dwarf traits and FF represents the ability for the dragons to breathe fire.

Also, if dd represents the normal traits and ff represents the inability of the dragons to breathe fire.

Then; we can cross a dominant trait for dwarfism which has a heterozygous trait for fire with a recessive trait of normal and nonfire.

The two parental gametes are: ddff  and DDFf

Using a Punnet Square:

         DF              Df

df      DdFf           Ddff

df      DdFf           Ddff

From above; we could observe that the proportion of progenitors that will be dwarf and at the same time unable to breathe fire is 50%.

Answer:

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Explanation:

Answer: D. Organisms that reproduce asexually create a large amount of offspring in a short period of time in order to maintain their population.

Explanation:

When an organism is able to reproduce asexually as opposed to sexually, it means that they do not require a mate to make offspring. Offspring of such organisms will therefore receive all their genes from one source.

Such organisms are able to reproduce very fast when they are presented with adequate conditions especially because they do not need another organism to do so. They will neither have to waste much energy nor have to go through the whole sexual process so they will be able to produce lots of offspring.

Animals are known to have offspring through asexual and/or sexual reproduction. The choices that has an argument for the advantages of asexual reproduction is that Organisms that reproduce asexually create a large amount of offspring in a short period of time in order to maintain their population.

The offspring are regarded as clones that derives its root from the original parent.

A single individual can have offspring asexually and also in large numbers quickly.

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Answer:

Tumors constantly undergo mitosis.

Explanation:

Tumors are (generally) considered to be cancerous; therefore, they divide uncontrollably. Tumors undergo mitosis just like any other cell in your body but can be dangerous over time if not dealt with.

Answer:

What is cancer and what does it have to do with mitosis?

Cancer: mitosis out of control

Mitosis is closely controlled by the genes inside every cell. Sometimes this control can go wrong. If that happens in just a single cell, it can replicate itself to make new cells that are also out of control. These are cancer cells.

Explanation:

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Answer:

Systems of specialized cells within organisms help them perform the essential functions of life, which involve chemical reactions that take place between different types of molecules, such as water, proteins, carbohydrates, lipids, and nucleic acids. All cells contain genetic information in the form of DNA molecules.

Answer:

b

Explanation:

Answer:

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Explanation:

你可以在书中找到

Answer:

Pangea refers to the one, large, solid land mass that is believed to have existed before the continents divided.

Explanation:

Pangea is often the explanation for tectonic plates, as they are believed to have been a by-product of the split of Pangea well over a million years ago.