Answer:
Crossing-over between homologous chromosomes (prophase 1), the random lining of homologous chromosomes (metaphase 1), and random fertilization are the mechanisms involved in genetic variation.
Explanation:
Crossing-over between homologous chromosomes (prophase 1), the random lining of homologous chromosomes (metaphase 1), and random fertilization are the mechanisms involved in genetic variation.
The Crossing-over events occur between two homologous chromosomes in the equatorial plane and make the daughter cells genetically different from the original one. The Chiasma is the position where two homologous chromatids interchange genetic information, giving a place for new genetic material or information to be provided to descendants. After crossing over, homologous chromosomes get separated again.
On the equatorial plane, homologous paired together, randomly aline with their kinetochores facing opposite poles. The random arrangement of tetrads is different in every cell going through the meiosis process. There is no equal alinement between two cells. When tetrads aline in the equatorial plane, there is no predetermined order for each of the homologous chromosomes of each tetrad to face one of the poles and then migrate to it while separating. Chromosomes of the homologous pair arrange to face any of the poles to migrate forward to it. Each of the chromosomes has two possibilities for orientation at the plane. When the new haploid cells are formed, the number of variations in each cell is also different and depends on the chromosomes that form that cell. The order in the equatorial plane is what introduces variation into the gametes, being almost impossible for two gametes to have the same genetic charge.
Independent assortment occurs when the alleles from two or more different genes distribute in gametes independently from each other. In other words, a gamete receives an allele from a gene that does not depend on nor influence the allele of another gene in the same gamete. This can only be applied to independent genes. An organism gets only one of the members of the chromatids pair of each parent.
Concerning the balance of pollutants in the biosphere, Scientists have proved that the natural system of the earth is overwhelmed by pollution.
Answer:
If the scull is fused the individual is not a baby
Explanation:
If a skull is found, one of the first things to do is classify by age. Careful observation will show that the skull may or may not be fused. Noteworthy observations could give the professional an idea of the individual's age.
In the womb when the bones of the skull are being formed thre are typically seven bones with gaps in between. This allows the infant to pass safely through the birth canal but giving way to squeezing and the contractions of the uterus. After the child is born there are still remaining gaps. These gaps allow the brain to grow and develop without pressure from the skull. This can often be observed by a soft spot on the top of the infant's head sometimes called a "mole"
Around two years of age, these bones begin to fuse and harden. Therefore if a skull is found with fused bones, the individual can be placed to be older than two years of age. Other determining factors such as teeth etc can narrow down the individual's age.
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Answer:</h2>
Blood Is A Heterogeneous mixture.
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Explanation:</h2>
Heterogeneous mixture is a mixture that is made up of different substance that remains physically separated which means the cell organelles (Red blood cells, white blood cells, platelets etc.)present in blood does not mix completely and hence get precipitated after kept still for a while.
There are three ways to identify a Heterogeneous mixture.
- It has chunks of stuff that you are able to see with your eyes.
- It appears cloudy(blur).
- After a while, the substance will separate into layers at settle at the bottom(gets precipitated).
Result: Blood is a Heterogeneous mixture
