Answer:
The functional unit of a muscle cell is known as a "sarcomere" which covers the distance between the two Z-lines.
The sarcomere consists of A-zone which contains both thick and thin filaments, H-zone which contains only thick filaments and I band which contains only thin filaments.
During muscle contraction, thick and thin myofibrils slide over each other due to which the distance between two z-line get reduced.The H and I zone gets shortened but A zone does not shorten but come close to other A- bands and disappears.
B) Polymerases can only synthesize in the 5' to 3' direction
C) There are only enough dNTP's to support quick replication on one strand, so the other strand lags behind it
D) It is necessary to "slow down" one of the strands so that replication does not occur before cells have a chance to grow
Answer:
B) Polymerases can only synthesize in the 5' to 3' direction
Explanation:
The leading strand's directionality is 3' to 5', so polymerase has no problem with replicating this one. But the lagging strand has the opposite directionality, so the polymerase must work in the opposite direction of the replication fork.In consequence, the replication process undergoes periodic breaks, and the enzymes have to stop and start again while helicase separates both strands, resulting in the polymerization of okazaki fragments.
Answer: The Leber's hereditary optic neuropathy (LHON) is caused by defective genes contained in mitochondrial DNA.
Explanation:
LHON is causes the vision loss. This occurs due to mutation in the mitochondrial DNA. The symptoms are not associated vision loss thus it is difficult to predict that which member of family was the carrier of the disease. Some people do not get completely blind. A young male is expected to develop a risk of 50% development of this disease.
Students have been assigned to write reports on cell organelles. Eric's report is about the organelle that supports and gives structure to plant cells. Which organelle is Eric writing about?
O cell wall
cell membrane
cytoplasm
O nucleus
B. Removes waste from the body
C. Attaches to bones helps the body move
D. The nervous system gathers and interprets information and sends messages throughout the body.
Answer:
A
Explanation:
please give brainlest
Imagine you want to conduct an experiment to understand how just one of these variables differs in a local lake, depending on its depth. This lake reaches a depth of 17 meters. For this activity:
Pick a variable that might change as you go deeper in the lake on a given day.
Do a little research on that variable to determine how you might measure it in a lake.
Use the template below to outline an experiment to investigate this variable in the lake by depth. For each part, simply answer the question in parentheses to create your outline.
Type your response to each field in the space below that field:
Title: (Enter a brief, descriptive title. Hint: Sometimes it’s best to do this las
Complete question:
Fish are sensitive to many environmental variables: dissolved oxygen, light, temperature, pH, clarity of the water, food supply, presence of predators, etc. Fish will be attracted to different locations in a lake, based on its mix of variables.
Imagine you want to conduct an experiment to understand how just one of these variables differs in a local lake, depending on its depth. This lake reaches a depth of 17 meters. For this activity:
Pick a variable that might change as you go deeper in the lake on a given day.
Do a little research on that variable to determine how you might measure it in a lake.
Use the template below to outline an experiment to investigate this variable in the lake by depth. For each part, simply answer the question in parentheses to create your outline.
Type your response to each field in the space below that field:
Title: (Enter a brief, descriptive title. Hint: Sometimes it’s best to do this last.)
Purpose: (Why are you doing this experiment?)
Hypothesis: (What do you predict from this experiment and why?)
Procedure/Method: (How will you specifically carry out your experiment to test your prediction?)
Observations: (What specifically would you look for and record?)
Data analysis: (With this kind of data, what would be the best way to present it?)
Conclusion: [No need to enter anything here for now.]
References: (List any references you used to design the experiment. Note that for a full experiment write-up you’d also list any references you used while carrying out the experiment or in analyzing your results.)
Answer and Explanation:
Variable: dissolved oxygen
Title:Oxygen variation as a water quality indicator.
Purpose: To study how dissolved oxygen varies with depth
Hypothesis: The percentage of dissolved oxygen will decrease as depth increases.
Procedure/Method:
Observations:
%DO in each site and depth will be recorded in order to analyze how it varies with depth.
Data analysis:
According to different indicators of water quality in a lake, the observed %DO will be compared and analyzed to evaluate the sanity state of the lake water. Example of valuation scale,
NORMAL index: Oxygen concentration in the water column is found to be sufficient for the fish survival
REGULAR: Decrease in oxygen concentration at greater depth, values below saturation in the background
CRITICAL: Null oxygen concentration in all or part of the column profile of water. Probable fish mortality events.
According to the taken data, observations on the study site will be taken, such as the variation in oxygen concentration as it gets deeper, until reaching hypoxia level, where fishes can not survive. Data can be presented in tables and in graphs, in both cases comparing sampling sites and depth, making a focus on the valuation scale.
Conclusion:
Association of the oxygen variation with the sanity state of the lake, microbiology decomposition processes at different depths, eutrophication state, among others.
References:
- Quality monitoring in San Roque waters. INA-CIRSA. 02/26/2013
- Quality Monitoring Program of Water from Los Molinos Reservoir. Articulation and Institutional Synergy for the Water Resources Preservation. Cossavella A, Bazan R. 2018
- Limnology course. Córdoba National University, UNC, 2018
Answer:
Explanation:
The scenario is the following.
A population of yellow lizards lives on an island where there is no natural predator. Males of the species use the yellow color to attract females in reproductive seasons. The brighter the males are, the better their genetic quality is. Females are also yellow, but not as bright as males.
A new hawk species was introduced into the island to control some farm pests. But this hawk species prefer to feed on the lizards. The yellow color of these animals contrasts with the dark background and can be easily seen from the air. So the lizard population suffers from significant predation affecting its size sharply.
Some of the lizards then suffer from a mutation and change their color from yellow to greyish brown, which turns to be better to camouflage on the rocks and get to survive. Individuals with greyish brown color get to reproduce at a higher rate than yellow individuals, who keep being hunted by the hawk.
Eventually, after many generations, the yellow individuals decrease to near zero in the population, while greyish brown individuals increase significantly, with males still being brighter than females.
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Natural selection is an evolutive force that can act favoring an allele or against it, according to how it affects the fitness of individuals. Natural selection selects beneficial alleles and increases their frequency in the population.
When many organisms in a population sharing the same trait die, it is because they did not have good fitness, so they were not adapted to the environment and its pressures. The alleles coding for that trait were not good for the fitness of the animals, so they do not get to survive.
These individuals die before reproducing, so they could not transfer their genetic charge to the following generation. Eventually, the alleles coding for the trait will decrease in the population, probably near zero. Natural selection is acting against this phenotype. Other alleles will be beneficiated, and their frequency in the population will increase.
This change in alleles frequency is what we call adaptation.
Natural selection results in adaptation, which means the increase of the aptitude phenotype. Aptitude is the contribution of each genotype to the next generation.
In many cases, adaptations can be correlated to environmental factors or selective pressures applied by other organisms or habitats.
Let us remember that a mutation is a change or alteration in DNI sequences that introduce new variants. Many of these are eliminated, but some of them might succeed and be incorporated into each individual. These mutations are the ones that have been selected by natural selection.
So, in the exposed example, we are focussing on the lizards population.
• The selective pressure or modeling environmental factor is predation by the introduced hawk.
• The lizards´ response to predation is the survival of only those that carry mutations ⇒ greyish brown color
• Natural selection benefits these mutations.
• Greyish brown lizards survive and increase their fitness.