The themes of the Biology test at Enem are varied and, for the most part, cover the most current issues.
In general, the Biology exercises that most fall in Enem are related to Ecology, Anatomy and Human Physiology, Genetics and Cytology.
question 1
(Enem/2018)
Ecological corridors aim to mitigate the effects of ecosystem fragmentation by promoting the link between different areas, with the objective of providing the displacement of animals, the dispersion of seeds and increased coverage vegetable. They are instituted based on information such as studies on the displacement of species, their home range (area necessary for the supply of their vital and reproductive needs) and the distribution of their populations.
Available at: www.mma.gov.br. Accessed on: Nov. 30 2017 (adapted)
In this strategy, the recovery of biodiversity is effective because:
a) provides gene flow.
b) intensifies species management.
c) expands the process of human occupation.
d) increases the number of individuals in populations.
e) favors the formation of fully protected islands.
The correct answer is option a) provides gene flow.
Gene flow corresponds to increased diversity from a genetic point of view. In this way, ecological corridors allow the movement of animals and the dispersal of seeds.
This results in an increase in vegetation cover which, in turn, allows living beings to interbreed.
The other alternatives are wrong because:
b) Species management has the characteristic of controlling possible damage and negative consequences caused to society and even to the ecological niche.
c) The process of human occupation is not related to ecological corridors.
d) The strategy presented in the statement is not related to the increase in the number of individuals.
e) Ecological corridors do not favor the formation of fully protected islands.
question 2
(Enem/2018)
Insects can show three types of development. One of them, holometabolia (complete development), consists of the egg, larva, pupa and sexually mature adult stages, which occupy different habitats. Insects with holometabolia belong to the most numerous orders in terms of known species. This type of development is related to a greater number of species due to the
a) protection in the pupal stage, favoring the survival of fertile adults.
b) production of many eggs, larvae and pupae, increasing the number of adults.
c) exploration of different niches, avoiding competition between life stages.
d) food intake at all stages of life, ensuring the emergence of the adult.
e) use of the same food in all phases, optimizing the body's nutrition.
The correct answer is option c) exploration of different niches, avoiding competition between stages of life.
Each stage of development has a different habitat and niche, which prevents competition between species, that is, intraspecific competition. Thus, the effectiveness of the animal within its environment is increased, as well as its adaptation to the environment.
The other alternatives highlight existing stages of development, but they are not related to the increase in the number of species nor to the justification presented.
question 3
(Enem/2018)
Pollination, which enables the transport of pollen grain from one plant to the stigma of another, can be
performed biotically or abiotically. In abiotic processes, plants depend on factors such as wind and water.
The evolutionary strategy that results in more efficient pollination when it depends on the wind is (a):
a) decrease of the chalice.
b) elongation of the ovary.
c) availability of nectar.
d) intensifying the color of the petals.
e) increase in the number of stamens.
The correct answer is option e) increasing the number of stamens.
Wind pollination only occurs in the presence of a large amount of pollen, otherwise, it is considered that the wind does not do directional pollination. The number of stamens determines the amount of pollen.
question 4
(Enem/2018)
The desert is a biome located in regions with low humidity. The fauna is predominantly composed of rodents, birds, reptiles and arthropods.
An adaptation, associated with this biome, present in living beings of the aforementioned groups is (a):
a) existence of numerous sweat glands in the epidermis.
b) elimination of nitrogenous excreta in a concentrated form.
c) development of the embryo inside an egg with shell.
d) ability to control body temperature.
e) breathing performed by foliaceous lungs.
The correct answer is option b) elimination of nitrogenous excreta in a concentrated form.
Sweat and perspiration are a characteristic of mammals and the statement mentions rodents, birds, reptiles and arthropods. Rodents, in particular, do not hatch from eggs, eliminating yet another alternative.
Foliaceous lungs have simple structures and are not found in the animals mentioned in the statement. Thus, we emphasize that the elimination of nitrogenous excreta in a concentrated form is a strategy of the individuals mentioned.
question 5
(Enem/2018)
The use of extracts of natural origin has received the attention of researchers around the world, mainly in developing countries that are highly affected by infectious diseases and parasitic. A good example of this use are botanical products that fight insects.
The use of these products can help control:
a) schistosomiasis.
b) leptospirosis.
c) leishmaniasis.
d) leprosy.
e) AIDS.
The correct answer is option c) leishmaniasis.
Leishmaniasis is a disease caused by a protozoan, transmitted through the bite of an insect vector. There is medication to prevent the disease in humans only.
The other alternatives are wrong because:
a) Schistosomiasis is a parasitic infectious disease, but its prevention and control must be carried out with basic sanitation actions.
b) Leptospirosis is a serious bacterial disease and its prevention is mainly related to basic sanitation and hygiene.
d) Leprosy is a chronic disease caused by bacteria and its prevention is based on specific treatment and hygiene.
e) AIDS is a disease caused by the HIV virus and the fight against its spread is done through health campaigns.
question 6
(Enem/2018)
To be absorbed by human gut cells, ingested lipids must first be emulsified. At this stage of digestion, the action of bile acids is necessary, since lipids are non-polar in nature and are insoluble in water.
These acids act in the process to:
a) hydrolyze the lipids.
b) act as detergents.
c) make the lipids amphiphilic.
d) promote lipase secretion.
e) stimulate the intestinal transit of lipids.
The correct answer is option b) act as detergents.
Bile acids have the function of separating and facilitating digestion. They act as detergents on fats (lipids).
question 7
(Enem/2017)
Cell therapy has been widely publicized as revolutionary, as it triggers tissue regeneration from new cells. However, the technique of introducing new cells into tissue, for the treatment of illnesses in individuals, was already routinely applied in hospitals.
What technique does the text refer to?
a) vaccine.
b) biopsy.
c) hemodialysis.
d) chemotherapy.
e) blood transfusion.
The correct answer is option e) blood transfusion.
In blood transfusion, the transfer of blood cells occurs, where the recipient individual receives cells such as red blood cells and leukocytes.
The other alternatives are wrong because:
a) the vaccine represents an injection of a virus or bacteria and not a human cell.
b) Biopsy is the removal of tissue.
c) Hemodialysis does not insert cells, it is a procedure that helps the function of filtering the blood.
d) Chemotherapy is related to a chemical substance.
question 8
(Enem/2018)
In the cell cycle, regulatory molecules act. Among them, the p53 protein is activated in response to DNA mutations, preventing the cycle from progressing until the damage is repaired, or inducing the cell to self-destruction.
ALBERTS, B. et. al. Fundamentals of Cell Biology. Porto Alegre: Artmed, 2011 (adapted)
The absence of this protein may favor:
a) reduction of DNA synthesis, accelerating the cell cycle.
b) immediate exit from the cell cycle, anticipating DNA protection.
c) activation of other regulatory proteins, inducing apoptosis.
d) maintenance of genetic stability, favoring longevity.
e) exaggerated cell proliferation, resulting in the formation of a tumor.
The correct answer is option e) exaggerated cell proliferation, resulting in the formation of a tumor.
The protein mentioned in the statement, p53, when absent, causes the uncontrolled cell cycle, thus providing the accumulation of cells. In this way, the malignant tumor is formed.
question 9
(Enem/2018)
One student reported that the mapping of the barley's DNA was almost complete and its genetic code unraveled. He drew attention to the number of genes that make up this genetic code and that the barley seed, despite small, it has a more complex genome than the human, and much of this code is made up of sequences repeated. In this context, the concept of genetic code is wrongly approached.
Scientifically this concept is defined as:
a) broken nucleotides that encode the amino acids.
b) location of all genes found in a genome.
c) encoding of repeated sequences present in a genome.
d) set of all messenger RNAs transcribed in an organism.
e) all base pair sequences present in an organism.
The correct answer is option a) broken nucleotides that encode the amino acids.
The genetic code is made up of broken nucleotides that are the codons that, in turn, encode the natural amino acids.
question 10
(Enem/2017)
Duchenne muscular dystrophy (DMD) is a disease caused by a mutation in a gene located on the X chromosome. Researchers studied a family in which monozygotic twins carried a recessive mutant allele for this gene (heterozygous). Interestingly, one of the twins had the phenotype related to the mutant allele, ie, DMD, while her sister had the normal phenotype.
RICHARDS, C. S. et al. The American Journal of Human Genetics, no. 4, 1990 (adapted)
The difference in the manifestation of DMD between the twins can be explained by:
a) incomplete dominance of the mutant allele in relation to the normal allele.
b) failure to separate the X chromosomes at the time of separation of the two embryos.
c) chromosomal recombination in an embryonic cell division prior to the separation of the two embryos.
d) random inactivation of one of the X chromosomes at a stage after the division that results in the two embryos.
e) paternal origin of the chromosome carrying the mutant allele in one of the twins and maternal origin in the other.
The correct answer is option d) random inactivation of one of the X chromosomes at a stage after division that results in the two embryos.
In these cases, the two twins are considered to have inactivated the X chromosomed , but one of them is not a carrier, while the other has the disease.
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