Answer:
Natural selection is generally limited to modifying structures that were present in previous generations and in previous species
Explanation:
The basic idea of biological evolution is that populations and species of organisms change over time. Today, when we think of evolution, we are likely to link this idea with one specific person: the British naturalist Charles Darwin.
In the 1850s, Darwin wrote an influential and controversial book called On the Origin of Species. In it, he proposed that species evolve (or, as he put it, undergo "descent with modification"), and that all living things can trace their descent to a common ancestor.
Natural selection, genetic drift, and gene flow are the mechanisms that cause changes in allele frequencies over time. When one or more of these forces are acting in a population, the population violates the Hardy-Weinberg assumptions, and evolution occurs. The Hardy-Weinberg Theorem thus provides a null model for the study of evolution, and the focus of population genetics is to understand the consequences of violating these assumptions.
New gene variants (i.e., alleles) are produced by random mutation, and over the course of many generations, natural selection may favor advantageous variants, causing them to become more common in the population.
<span>An incorrect number of
chromosomes is the most common form of genetic disorder that causes the fetus
to spontaneously abort. </span>The
human cells normally contain 23 pairs of chromosomes, for a total of 46
chromosomes in each cell. Error in one or more of the meiosis, mitosis,
maternal age, or environment are the possible cause of the chromosome
abnormalities. These abnormalities in the number chromosomes can cause problems
with development, growth and function of the body's systems. These changes can
occur in early fetal development, or in any cell after birth during the
formation of reproductive cells (sperm and eggs).
As a leaf cell is a plant cell contains chloroplasts for photosynthesis which the root hair cell does not have, leaf cell also contains larger vacuoles and the presence of a cell wall.
Answer:
A. The number of cells that are dying is balanced by the number of new cells that are being formed.
C. Harmful waste products may be accumulating.
D. The cells are likely running out of nutrients.
Explanation:
During the stationary phase, the number of viable cells remains constant. This may be due to a balance between cell division and cell death wherein the total number of newly formed cells and the cells undergoing death are equal.
Nutrient limitation is one of the several factors that make the microbial cells to enter the stationary phase. Depletion of nutrients slows down the population growth.
Accumulation of toxic waste products as it occurs during the growth of anaerobic bacteria also adversely affects the population growth.
For example, the accumulation of lactic acid and other organic acids (by-products of anaerobic respiration) inhibits the growth of the population by making the medium acidic.
Answer:
Advantageous
Explanation:
Natural selection acts on traits that are advantageous, thus increasing chances of survival and passing on the trait.
