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3 years ago

Which zone undergoes the least amount of change in a given day, resulting in a high level of biodiversity?

Biology

2 answers:

Gala2k [10]3 years ago

6 0

The answer is: Middle intertidal zone which is also known as littoral zone, undergoes the least amount of change

Explanation:

Middle intertidal zone is the area above the water at low tide and underwater at high tide. Moreover, the region that lies between the tide marks may include numerous habitats like starfishes etc. However, due to high temperature and long periods of dryness, organisms in this particular area are not well adapted which results in a high biodiversity.

andrew-mc [135]3 years ago

5 0

The middle intertidal zone undergoes the least amount of change

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4) A homozygous groucho fly ( gro, bristles clumped above the eyes) is crossed with a homozygous rough fly (ro, eye abnormality)

docker41 [41]

Answer and Explanation:

A homozygous groucho fly ( gro, bristles clumped above the eyes) is crossed with a homozygous rough fly (ro, eye abnormality).

The F1 females are testcrossed, producing these offspring: groucho 518 rough 471 groucho, rough 6 wild-type 5 1000 a) What is the linkage distance between the two genes? B) Plot the genes on a map c) If the genes were unlinked and the F1 females were mated with the F1 males, what would be the offspring in the F2 generation?

1st cross:

Parental) grogro ro+ro+ x gro+gro+ roro

F1) gro+gro ro+ro

2nd cross:

Parental) gro+gro ro+ro x grogro roro

Gametes) gro+ro+ gro ro

gro+ro gro ro

gro ro+ gro ro

gro ro gro ro

Punnet square)

gro+ro+ gro+ro gro ro+ gro ro

gro ro gro+gro ro+ro gro+gro roro grogro ro+ro grogro roro

F2)

0.518 grogro ro+ro (518 individuals)

0.471 gro+gro roro (471 individuals)

0.006 grogro roro (6 individuals)

0.005 gro+gro ro+ro (5 individuals)

Total number of individuals 1000

Note: These frequencies were calculated dividing the number of individuals belonging to each genotype by the total number of individuals in the F2.

To know if two genes are linked, we must observe the progeny distribution. If individuals, whos genes assort independently, are test crossed, they produce a progeny with equal phenotypic frequencies 1:1:1:1. If we observe a different distribution, that is that phenotypes appear in different proportions, we can assume that genes are linked in the double heterozygote parent.

In the exposed example we might verify which are the recombinant gametes produced by the F1 di-hybrid, and we can recognize them by looking at the phenotypes with lower frequencies in the progeny.

By performing this cross we know that the phenotypes with lower frequencies in the progeny are groucho, rough and wild-type. So the recombinant gametes are gro+ro+ and gro ro, while the parental gametes are gro+ro and gro ro+.

So, the genotype, in linked gene format, of the double heterozygote individual in the F1 is gro+ro/gro ro+.

To calculate the recombination frequency we will make use of the next formula: P = Recombinant number / Total of individuals. The genetic distance will result from multiplying that frequency by 100 and expressing it in map units (MU). One centiMorgan (cM) equals one map unit (MU).

The map unit is the distance between the pair of genes for which one of every 100 meiotic products results in a recombinant product.

The recombination frequency is:

P = Recombinant number / Total of individuals

P = 6 + 5 / 1000

P = 11 / 1000

P = 0.011

The genetic distance between genes, is 0.011 x 100= 1.1 MU.

Genetic Linkage Map:

Parental Phenotypes)

-----gro+------ro---- -----gro------ro+----

----- gro ------ro---- ---- gro------ ro ----

Recombinant phenotypes)

-----gro+------ro+---- -----gro------ro----

----- gro ------ ro---- -----gro------ro----

If the genes were unlinked and the F1 females were mated with the F1 males, the offspring in the F2 generation would have been

4/16 = 1/4 gro+gro ro+ro

4/16 = 1/4 gro+gro roro

4/16 = 1/4 grogro ro+ro

4/16 = 1/4 grogro roro

Their phenotypic frequencies would be 1:1:1:1 related.

7 0

3 years ago

Question 3 and 5 help please!

sasho [114]

The answer to 3. is B

7 0

3 years ago

Which of these cells of the dermal tissue of plants prevent water loss and control gas exchange?

masha68 [24]

The answer is guard cells.
Guard cells are cells surrounding each stoma. They help regulate the rate of transpiration by opening and closing the stomata. They are specialized cells in the epidermis of leaves, stems and other organs that are used to control gas exchange. They are produced in pairs with a gap between them that forms a stomatal pore (stoma).

4 0

3 years ago

Read 2 more answers

Explain how the following factors support the mechanisms of evolution: a. b. Gene Flow

vladimir1956 [14]

1.- Natural Selection

Natural Selection leads to an evolutionary change when some individuals with certain traits in a population have a higher survival and reproductive rate than others and pass on these inheritable genetic features to their offspring. Evolution acts through natural selection whereby reproductive and genetic qualities that prove advantageous to survival prevail into future generations. The cumulative effects of natural selection process have giving rise to populations that have evolved to succeed in specific environments. Natural selection operates by differential reproductive success (fitness) of individuals.

The Darwin’s Finches diagramillustrates the way the finch has adapted to take advantage of feeding in different ecological niches:

2.- Genetic Drift

Random Drift consists of random fluctuations in the frequency of appearance of a gene, usually, in a small population. The process may cause gene variants to disappear completely, thereby reducing genetic variability. In contrast to natural selection, environmental or adaptive pressures do not drive changes due to genetic drift. The effect of genetic drift is larger in small populations and smaller in large populations.

Genetic drift is a stochastic process, a random event that happens by chance in nature that influences or changes allele frequency within a population as a result of sampling error from generation to generation. It may happen that some alleles are completely lost within a generation due to genetic drift, even if they are beneficial traits that conduct to evolutionary and reproductive success. Allele is defined as any one of two or more genes that may occur alternatively at a given site (locus) on a chromosome. Alleles are responsible for variations in a trait.

The population bottleneck and a founder effect are two examples of random drift that can have significant effects in small populations. Genetic drift works on all mutations and can eventually contribute to the creation of a new species by means of the accumulation of non-adaptive mutations that can facilitate population subdivision.

In population genetics, Gene Flow(also known as gene migration) refers to the transfer of genes from the gene pool of one population to another. Gene flow may change the frequency and/or the range of alleles in the populations due to the migration of individuals or gametes that can reproduce in a different population. The introduction of new alleles increases variability within a population and allows for new combinations of traits. Horizontal gene transfer (HGT) also known as lateral gene transfer (LGT), is a process in which an organism (recipient) acquires genetic material from another one (donor) by asexual means. It is already known that HGT has played a major role in the evolution of many organisms like bacteria. In plant populations, the great majority of cases linked to this mechanism have to do with the movement of DNA between mitochondrial genomes. Horizontal gene transfer is a widespread phenomenon in prokaryotes, but the prevalence and implications of this mechanism in the evolution of multicellular eukaryotes is still unclear. Nevertheless, many investigations on HGT in plants have been carried out during the last years trying to reveal the underlying patterns, magnitude and importance of this mechanism in plant populations as well as its influence on agriculture and the ecosystem.

Plant populations can experience gene flow by spreading their pollen long distances away to other populations by means of wind or through birds or insects (bees, for example) and once there, this pollen is able to fertilize the plants where it ended up. Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes (comparable to sperm cells). Of course, pollination does not always lead to fertilization.

Maintained gene flow also acts against speciation by recombining the gene pools of different populations and in such a way, repairing the developing differences in genetic variation.Thus, gene flow has the effect of minimizing the genetic differences between populations.

Human migrations have occurred throughout the history of mankind and are defined as the movement of people from one place to another. However, in a genetic context, this movement needs to be associated with the introduction of new alleles into a population through successful mating of individuals from different populations.

7 0

3 years ago

Which of the following terms describes a lipid molecule that has only single

schepotkina [342]

Answer:

Saturated fatty acids have only single bonds between carbon atoms. As a result, the carbon atoms are bonded to as many hydrogen atoms as possible. In other words, the carbon atoms are saturated with hydrogens. Saturated fatty acids are found in fats.

8 0

3 years ago