It is accurate to say that the repolarization of the atria is not visible on an ECG because the T wave of the ventricles obscures it.
How come atrial repolarization is obscured?The wave of atrial repolarization is of little amplitude, undetectable. A typical P wave has a maximum height of 2.5 mm (two and a half 1-mm divisions) and a maximum width of 120 ms (three 1-mm divisions) in any lead.
Where in the ECG is atrial repolarization concealed?Abbreviations. The electrocardiographic (ECG) deflection brought on by atrial depolarization is minimal in both amplitude and area when compared to the QRS complex. The subsequent QRS complex frequently obscures atrial repolarization.
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how are mutation and sexual reproduction involved in creating and maintaining variation in a population
Answer:
Mutation and sexual reproduction are two essential processes that contribute to creating and maintaining variation in a population.
Mutation is the ultimate source of genetic variation in a population. It is a random process that generates new alleles or genetic variations in an organism's DNA. Mutations can arise due to various factors such as exposure to radiation, chemicals, or errors during DNA replication. These mutations can be beneficial, harmful, or neutral, and they can change the physical traits of an individual.
Sexual reproduction involves the fusion of gametes from two parents to produce offspring that inherit traits from both parents. The process involves the mixing and recombination of genetic information from each parent, resulting in a unique combination of genes in the offspring. Sexual reproduction can introduce new genetic variations into the population and shuffle existing genetic variations, resulting in an increase in genetic diversity.
Both mutation and sexual reproduction work together to create and maintain genetic variation in a population. Mutations provide the raw material for genetic variation, while sexual reproduction shuffles and recombines this variation. The combination of these two processes leads to the creation of unique genetic combinations, which can help populations adapt to changing environmental conditions and evolve over time.
Explanation:
Reviewing Key Concepts: Major Evolutionary Milestones
Answer:
Porifera Sponges - Multicellular
Cnidaria Jellies- True tissues
Platyhelminthes Flatworms
Bilateral symmetry, Cephalization, Triploblastic
Nematoda Round Worms - Body Cavity
Mollusca Mollusks - Body Cavity, Nervous systems, Messenteries
Annelida True Worms - Segmentation, Specialization of gut areas
Arthropoda Buggity Bugs - Jointed appendages, Highly developed cephalization
Echinodermata Sea(stars, urchins, cucumbers) -Deuterostome development
Chordata and Subphylum Vertebrata - Internal skeletal support
Agnatha - Endoskeleton, Cranium
Chondrichthyes - Jaws, Paired fins
Osteichthyes - Calcified bones, Lateral lines
Amphibia - Supportive limbs, Double loop circulation, Lungs, Tympanum
Reptilia - Amniotic egg, Watertight skin, Alveoli, Heart with ventricular septum
Aves - Endothermy, Feathers, Hard shelled egg, Flight adaptations
Mammalia -Mammary glands, Highly developed brains
Explanation:
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Major Evolutionary Milestones are:
4.6 Billions years ago (BYA) - origin of Earth3.5 BYA= first life exist2.1 BYA= Eukaryotes exist1.2 BYA= Multicellular life occurs0.6 BYA= first animals occur0.5 BYA= Life move on land0.02BYA= Human beings occurIt is generally accepted that the Major Evolutionary Milestones of contemporary humans from our archaic ancestor involves four main stages:
Developing territorialityBipedalismA huge brain (encephalization)Civilization.These are the Hadean (4.6–4 billion years ago), Archean (2.5–4 billion years ago), Proterozoic (2.5–541 million years ago), and Phanerozoic (4.4–4.6 billion years ago) (541 million years ago to the present).
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The most likely cause of the changes in allele distribution is that the medium gray coloration in lizards appears to be a neutral mutant allele that allows the lizards to hide better from predators.
What is the cause of natural selection?Since black lizards are less able to hide from predators, the allele for black coloration decreases in frequency due to reduced fitness.
On the other hand, the medium gray coloration allows lizards to blend in with their environment, making them less visible to predators and increasing their chances of survival.
Therefore, the frequency of the gray allele increases over time as natural selection favors individuals with this allele.
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