The use of Punnett square in Mendel’s law helps in predicting the phenotype and genotypes from genetic crosses of offspring.
Explanation:
The study of trait inheritance in pea plants is performed by Gregor Mendel. He developed a model of pair of genes that specify the traits. There are different alleles of genes in a population of living organisms. His law of segregation states that one of the two copies of gene that is present in a specific organism gets distributed to gametes produced by it.
The F2 generation of gene is represented by Punnett model and by counting the squares of this model the genotype and the phenotype ratio can be predicted.
Desmosomes connects keratinocytes to each other. Why is this important?
Answer:
Desmosomes as structured are two adjacent attached cells formed in the cell membranes from protein plaques while connected by filaments. The function of separating an organism from its environment is performed by epithelial keratinocytes.
To protect the organism, the keratinocytes are connected by the desmosome filaments through adherence. The adhered keratinocyte / desmosome connection produces prekeratin, a fibrous protein that adds to the epidermis a soluble structure
A patient who was on chemotherapy is taking a new medication, which is available in a pre-filled syringe and is given subcutaneously.
Which statement by the patient during an assessment helps the nurse individualize the teaching plan?
"I used to administer subcutaneous injection to my father."
"I was instructed to take this medication the very next day after chemotherapy."
"I learned that this medication helps me reduce the risk of decreased immunity."
"A friend of mine who is undergoing chemotherapy was also prescribed this.
Answer:
"A friend of mine who is undergoing chemotherapy was also prescribed this.
Explanation:
it is a supporting statement
How did the lab activities help you answer the lesson question: How does human activity affect Earth’s freshwater resources? What did you learn from conducting this lab?
Answer:
Explanation:
In the lab, I observed how pollutants affect the pH of lakes and groundwater. Pollutants that result from human activity such as using soap and citric acid can change the pH of water. If the pH of the water changes, it might not be safe for people to drink that water or for organisms to live in it. I also learned that the pollution in a lake can end up in groundwater. Even though the soil can filter some pollutants and the water may look clean, its quality may not be good.
Answer:
In the l learned three main three main things that influence the freshwater available on earth: PH, pollutants and factory usage.
Explanation:
The first thing, PH, is really influenced by the way the pollutants are discarded, for example, if a factory decides to throw their pollutants inside a very good and not polluted river, this river will change how it chemically works, and through that, the PH will change, it can turn into a more acid or basic river, depending on the components that were thrown there.
I learned from conducting this lab that every act of the human race affects the environment as a whole, and the main thing to pay attention to in this experiment is that, everything is linked to one another in some way.
A scientist is using a computer model to predict changes to a population of rabbits in a meadow. Identify the information about the rabbit population that should be included in the computer model.
Answer:
In the mentioned case, the intrinsic and environmental factors influencing the size of the population should also be included in the computer model. The population size is primarily predicted by environmental and intrinsic factors.
The size of the population of any species is monitored by the factors like birth rate, death rate, limiting factors, and their accessibility, carrying capacity of the system, rate of migration, and others. All these elements should be taken into consideration in order to determine the changes observed in the population of rabbits in a meadow.
The fossil record resembles the living species in the same geographic area. How does this pattern support the theory of evolution by natural selection?
Answer:
The correct answer will be- species can change over time (assuming options are present)
Explanation:
The theory of evolution by natural selection by Charles Darwin suggests that species adapt to the changing environment and as a result changes over time.
The remnants of the organism that lived on the Earth gets buried under the earth and gets preserved. These preserved remnants of the organism are called the fossils which are collected and studied to understand the history of life on earth.
If the fossils collected on earth in a geographic area resembles the living species of the same geographic area provides a clue to the theory of natural selection suggesting that species can change over time as a result of natural selection.
Displacement of brain tissue under the falx cerebri or through the tentorial notch of the tentorium cerebelli is termed ____, and occurs with elevated ICP in one brain compartment with displacement of cerebral tissue toward an area of ___ pressure.
Brain herniation is displacement of brain tissue under the falx cerebri under the area of less pressure.
Brain herniation
Less
Explanation:
Brain herniation is disorder it occur due to the displacement of the cerebra in the brain. It is potentially deathly disorder when brain affected by high temperature or squeezing of the brain across the structure.
The tentorium is the dual fold in the brain, then it is an extension of the dura matter that separates cerebellum from cerebrum. There are two major types of herniation in the brain; that is supratentorial and infratentorial. The supretentorial is seen above the Tentorial notch.
Phytoplankton use sunlight to gain energy through photosynthesis. As a result of the Law of Conservation of Energy, phytoplankton cannot gain more energy than it consumes. A closed system consisting of an aquarium, phytoplankton, and sunlight is set up. Which of the following methods would best demonstrate the Law of Conservation of Energy? (3 points)
A) Measure the mass and temperature of the water. Then cover the aquarium to block the sunlight and measure the mass of the phytoplankton.
B) Change the closed system to isolated, so that energy can move out of it. Then measure the amount of energy that leaves.
C) Measure the mass of the phytoplankton before and after photosynthesis. Add the mass of the water.
D) Measure the amount of energy in the phytoplankton and the amount of light entering the aquarium. Then measure the amount of energy in the phytoplankton after exposure to the light and determine the difference.
E) Measure the amount of energy in the phytoplankton and the amount of light entering the aquarium. Then measure the amount of energy in the phytoplankton after exposure to the light and determine the difference.
Measure the amount of energy in the phytoplankton and the amount of light entering the aquarium. Then measure the amount of energy in the phytoplankton after exposure to the light and determine the difference.
Explanation:
Phytoplanktons like most of the plants use chlorophyll, sunlight and carbon di-oxide for photosynthesis but it depends on other organisms to consume extra energy as they are unable to gain enough energy from their consumption of light. This differs among the different species of planktons.
It can be observed in an aquarium that a phytoplankton is gaining less energy than the energy they have absorbed by the light and this can be done by measuring the energy before and after the photosynthesis.
New biosensors, applied like a temporary tattoo to the skin, can alert serious athletes that they are about to "hit the wall" and find it difficult to continue exercising. These biosensors monitor lactate, a form of lactic acid, released in sweat during strenuous exercise.
Which of the statements below is the best explanation of why athletes would need to monitor lactate levels?
A. During anaerobic respiration, lactate levels increase when muscles cells need more energy, however muscles cells eventually fatigue, thus athletes should modify their activities to increase aerobic respiration.
B. During aerobic respiration, muscles cells produce too much lactate which causes a rise in the pH of the muscle cells, thus athletes must consume increased amounts of sports drinks, high in electrolytes, to buffer the pH.
C. During anaerobic respiration, muscle cells receive too little oxygen and begin to convert lactate to pyruvate (pyruvic acid), thus athletes experience cramping and fatigue
D. During aerobic respiration, muscle cells cannot produce enough lactate to fuel muscle cell contractions and muscles begin to cramp, thus athletic performance suffers.
Answer:
The answer is letter A.
Explanation:
During anaerobic respiration, lactate levels increase when muscles cells need more energy, however muscles cells eventually fatigue, thus athletes should modify their activities to increase aerobic respiration.
DNA analysis of organisms can explain homologous structures in related species, but cannot explain analogous structures in seemingly unrelated species. Natural selection better explains analogous structures because_____________.
Answer:
To support the evolution, the anatomical features acts as the best evidence supporting the theory of evolution and its mechanism.
Studying the anatomical features led to the concept of homology which shows that organisms share homology in their structures independent of their habitat due to divergent evolution and analogy which evolved in different organisms sharing similar habitat resulting ion convergent evolution.
The analogous structures are considered better evidence to support the process of natural selection as the analogous organs represent the changes in the organs in response to the environment species is surviving and shows how species have changed compared to their ancestors.
Thus, analogous organs better explain natural selection.
A news article discussing the evolution of domestic dogs from wolves included this statement: "On its way from pack-hunting carnivore to fireside companion, dogs learned to love or at least live on wheat, rice, barley, corn, and potatoes." What is a more scientifically accurate way to state what happened with dogs?
Answer:
The answer is evolutionary purpose.
Explanation:
Some wolves may have had variants in their digestion that allowed them to eat wheat, rice, barley, corn, and potatoes, and so they were able to survive with humans.
Megan's mother suffered from the flu during her pregnancy with Megan. Statistically, this increases Megan's risk of developing schizophrenia later. This is an example of a(n) _____ factor, meaning a heritable change that is not due to DNA.
Answer:
Epigenetic
Explanation:
Epigenetic factors are factors that cause heritable changes in the expression of genes and not as a result of the DNA sequence of an individual. Factors such as lifestyle, age, complications during pregnancy etc, can have influence on the expression of genes as there is a change in a phenotype rather than the genotype being influenced.
Statistically, several studies have shown that complications during pregnancy increases the chance of a baby developing schizophrenia later on in life. Megan’s mother having suffered from flu during her pregnancy with Megan is an epigenetic factor that increases Megan’s chances of suffering from schizophrenia later.
What was rudolf virchow’s contribution to the cell theory?
Answer:
The credit of formulating cell theory is usually credited to two scientists that are Matthias Schleiden and Theodor Schwann but Rudolf Virchow was a well-known scientist who is known for his contribution to the cell theory.
In 1855 in his publication the statements were based on the observation about the cells that arise from pre-existing cells which he called Omnis cellula e cellula. Therefore after this publication, all accepted that new cell comes from the old cell which was early thought that new cells comes from fluid known as blastema.
So Rudolf Virchow contributed in the cell theory by popularizing the last theory of cell theory that says that new cells come from pre-existing cells.
He concluded that all cells come from preexisting cells.
Identify the structure that allows light to first enter the eye.
Answer:
Cornea
Explanation:
The first part of eye through which light enters into the eyes is cornea. Cornea comes in front of the pupil and iris and is made up of transparent layer. It is a curved structure just like a normal glass lenses and hence is able to focus light on retina. It also protects the eyes. Cornea along with anterior chamber is responsible for 67 percent of the optical power of eye and sends the light towards the pupil.
The genes for miniature wings (m) and garnet eyes (g) are approximately 8 map units apart on chromosome 1 in Drosophila. Phenotypically wild-type females (m + g / mg +) were mated to miniature-winged males with garnet eyes.
Part A
Which of the following phenotypic classes reflect offspring that were generated as a result of a crossover event?
Select all that apply.
garnet eyes
wild type
miniature wings
miniature wings, garnet eyes
Part B
If 800 offspring were produced from the cross, in what numbers would you expect the following phenotypes?
__wild type : __ miniature wings : __ garnet eyes : __ miniature wings, garnet eyes
Enter your answer as the number of flies of each phenotype separated by a colon (example: 100:300:100:300).
The following phenotypic classes reflect offspring that were generated as a result of a crossover event
wild typeminiature wingsgarnet eyesExplanation:
When the miniature wings and garnet eyes links up with the 8 map unit that are present between them. After that the presence of two recombinant classes must complement together and make 8% of total i.e. they contribute 4% each. together the parental classes make up to 92% by contributing 46% one.
This can be understood through a phenotypic ratio calculation, which can be expected from it.
wild type: 4% x 800 = 32
miniature wings: 46% x 800 = 368
garnet eyes: 46% x 800 = 368
miniature wings, garnet eyes: 4% x 800 = 368
True / False: The peripheral receptors located under the skin are very sensitive to to temperature changes and only provide feedback on to the hypothalamus (select one word answer only please).
Answer:
True
Explanation:
There are several specialized peripheral sensory neurons that are present beneath the skin known as nociceptors that are responsible for producing impulses whenever a dangerous stimulus such as extremely high or low temperature or pressure, chemical exposure, etc. is felt at the skin. The impulses produced are converted to long-range electrical signals and then transmitted to the brain cells for action
Hence, the given statement is true
Feather color in budgies is determined by two different genes, Y and B, one for pigment on the outside and one for the inside of the feather. YYBB, YyBB, YYBb or YyBb is green; yyBB or yyBb is blue; YYbb or Yybb is yellow; and yybb is white.
A blue budgie is crossed with a white budgie. Which of the following results is possible?
A) Green offspring only
B) Yellow offspring only
C) Blue offspring only
D) Green and yellow offspring
E) a 9:3:3:1 ratio
Answer:
Blue offspring only
Explanation:
If A blue budgie is crossed with a white budgie.
i.e yyBB or yyBb × yybb
let use yyBb for blue budgie,so we have; yB, yb, yB, yb representing the columns on the horizontal rows of the punnet square.
on the other hand, in white budgie yybb, we will have yb, yb, yb, yb representing the rows on the vertical column of the punnet square.
if a dihybrid cross occurs among these representative, all progeny in the punnet square will be yyBb, showing that they are all Blue offspring only.
Option D) Green and yellow offspring
The possible outcome of crossing a blue budgie (genotype yybb) with a white budgie (genotype yybb) is green and yellow offspring.
When a blue budgie (yybb) is crossed with a white budgie (yybb), all the offspring will have the genotype Yybb, resulting in a green feather color.
However, when a blue budgie (yybb) is crossed with a white budgie (yybb), there is a possibility of producing offspring with the genotype YYbb or Yybb, resulting in a yellow feather color.
Therefore, the possible outcomes are green and yellow offspring, represented by option D.
The brain area that regulates activities that control the state of wakefulness or alertness of the cerebral cortex is the :a. reticular formationb. pyramidsc. limbic systemd. thalamus
Answer:
a. reticular formation
Explanation:
The reticular formation is the functional system that spans the brain stem. It is composed of loosely clustered neurons present in white matter. The function of reticular formation is to regulate sensory input to the cerebral cortex and cortical arousal. It is also involved in the control of motor behavior.
Some of the neurons of the part of the reticular formation are known as the reticular activating system (RAS). These neurons send a continuous stream of impulses to the cerebral cortex and thereby keep the cortex alert and conscious. The impulses from RAS of reticular formation enhance the excitability of the cerebral cortex.
The impulses coming from all the great ascending sensory tracts also synapse with RAS neurons and serve to keep them active and enhance their stimulating effect on the cerebral cortex.
In prokaryotes, there are no membrane-bound organelles and no nuclear membranes. In addition, there are no mitochondria. Where are the electron transport chain and the ATP synthase working? What physical place are they in a prokaryotic cells?
Answer:
Prokaryotes lack membrane-bound organelle like mitochondria and chloroplast which is used by eukaryotes to synthesize ATP but ATP synthesis also takes place in prokaryotes. The electron transport chain and ATP synthetase of prokaryotic cells are embedded in the cell's plasma membrane of the prokaryotes.
The ATP synthesis in prokaryotes is similar to eukaryotes. NADH releases electrons to the electron carriers that are embedded in the plasma membrane which causes the translocation of H+ ions to the cell membrane outer face against the concentration gradient.
Then these electrons pass through the ATP synthetase which generates ATP for prokaryotic cell. So cell membrane is the physical place where ETC and ATP synthetase are present.
NEED HELP ASAP PLEASE WITH #16!!
Answer:
The correct option is D. 97%
Explanation:
Global warming can be described as the increase in the Earth's temperature over time. With the advancements in science and technology and with humans trying to make there lives on Earth better, one has to agree that humans have been destroying the Earth widely and increasing its temperature to cause global warming. Hence, no doubt that 97% of the climate scientists believe humans to be the cause of global warming.
The _______ of a phylogenetic tree represents the common ancestor, the _______ represent events where lineages diverged, and the _______ axis represents time. Assume that the tree is oriented as described in the textbook.
Answer:
a. root
b. nodes
c. horizontal
Explanation:
Systematics, as we have already indicated, is the part of science that tries to find out the degree of diversity and differentiation of organisms, as well as the kinships and affinities between them. This is based on the results of other disciplines such as Cytology, Anatomy, Palinology, Embryology, Phytochemistry, Genetics, Geobotany, etc. On the other hand, taxonomyi the part of the Systematics that deals with the theoretical study of classification (ordering of beings in class hierarchies), including in it its bases, principles, methods and laws; vegetable taxonomy, therefore, deals with the description, nomenclature and arrangement of living plants
Which of the following properties of transposable elements allows them to contribute to the C-value paradox?A. Their copy number can increase from one generation to the next.B. Their replication is controlled by genes found on the transposable element itself.C. Copies of transposable elements can appear on multiple chromosomes.D. All of these choices are correct.
Answer:
All of these choices are correct.
Explanation:
Transposons are the DNA sequences that can move from one location to another in the genome. The transposon genes are also known as jumping genes.
The C value paradox of the transposable elements depends on the different factors. The transposons can increase their number by copy and paste mechanism. The genes can be controlled by the enzyme transposase and their copies may exist at the different site of the chromosome.
Thus, the correct answer is option (D).
Why does pulse (and breathing rate) increase during exercise? (relate to cellular respiration)
Answer:
Explanation:
During exercise, the rate of breathing increases in order to fulfill the needs of oxygen required by the body for the release pf energy required. The body activity and muscles are in movement and required more energy than at rest. The absorbance of oxygen in to the blood increases which will increase the heart beat and also carbon dioxide starts removing from the blood. the lungs must provide more oxygen to the blood during the exercise.
so as the activity level increases, the demand for oxygen increase which will increase the breathing to take in more oxygen from outside in to lungs so that the lungs pump more oxygen to the hearth which will deliver to the muscles for activity.
Pulse and breathing rates increase during exercise to meet the higher oxygen demands of the muscles and repay the oxygen debt incurred. This heightened respiratory activity is due to several neural and chemical factors, including the immediate neural response to exercise and the need to restore cellular ATP. Breathing remains elevated post-exercise until the body's oxygen levels are normalized.
Explanation:During exercise, the body's demand for oxygen increases to support the intensified activity of the muscles. This increased demand leads to an oxygen debt, a condition where the body needs more oxygen than what has been supplied during the exercise. To meet this demand and repay the oxygen debt, there is a rise in pulse and breathing rate.
The increased breathing rate or hyperpnea, which includes both an increased rate and depth of breathing, ensures that more oxygen is taken into the lungs and transported to the muscles, while more carbon dioxide is expelled. This response is driven by several factors, including the body's immediate neural responses to exercise involving psychological stimuli, activation of motor neurons, and stimulation of proprioceptors, as well as the need to restore ATP and creatine phosphate levels, convert lactic acid to pyruvic acid, and maintain appropriate blood pH levels.
Density-dependent inhibition is a phenomenon in which crowded cells stop dividing at some optimal density and location. This phenomenon involves binding of a cell-surface protein to its counterpart on an adjoining cell's surface. A growth inhibiting signal is sent to both cells, preventing them from dividing. Certain external physical factors can affect this inhibition mechanism.
Select the statement that makes a correct prediction about natural phenomena that could occur during the cell cycle to prevent cell growth.
A) As cells become more numerous, they begin to squeeze against each other, restricting their size and ability to allow cell growth.
B) As cells become more numerous, the protein kinases they produce begin to compete with each other until only one cell has the proteins necessary for growth.
C) As cells become more numerous, the amount of required growth factors and nutrients per cell becomes insufficient to allow for cell growth.
D) As cells become more numerous, more and more of them enter the synthesis part of the cell cycle and duplicate DNA to inhibit cell growth.
Answer: C) As cells become more numerous, the amount of required growth factors and nutrients per cell becomes insufficient to allow for cell growth.
Explanation:
Growth factors are proteins that stimulate cell division.Two of the most important internal factors are kinases and cyclins. In most mammal cells stop dividing once they touch other cells this means that when a cell population reaches a certain density, the amount of required growth factors and nutrients available to each cell becomes insufficient to allow continued cell growth.
The correct prediction about a phenomenon that could occur to prevent cell growth during the cell cycle due to density-dependent inhibition is that as cells proliferate, they may not have enough growth factors and nutrients to support further growth.
C is correct
Explanation:Density-dependent inhibition is a key regulatory mechanism during the cell cycle that ensures cells stop dividing when they become overly crowded. This process involves the interaction of cell-surface proteins between adjacent cells which signal each other to halt division. One accurate prediction about natural phenomena that could prevent cell growth as a result of density-dependent inhibition is: C) As cells become more numerous, the amount of required growth factors and nutrients per cell becomes insufficient to allow for cell growth.
When cells reach a certain density, they may compete for limited resources such as nutrients and growth factors. The scarcity of these essential elements acts as a natural inhibitor of cell proliferation. This is distinct from the process wherein cells enter the synthesis phase of the cell cycle to duplicate DNA, or from the competition among protein kinases, which are not direct consequences of cell crowding. It is important to note that signaling pathways that involve proto-oncogenes and tumor suppressor genes are complex and include not only growth-promoting signals but also signals for inhibition of cell division, demonstrating that multiple factors can impact the cell cycle.
"Outline the process of_________.a. in vitro fertilisation including down-regulation.b. superovulation".c. harvesting.d. fertilization.e. implantation.
Answer:
The answer is letter A.
Explanation:
In virto fertilisation is a reproductive process, in which, embryos are produced after the extraction of the egg and the sperm from the childless couple.
First the woman is submited to a threatment to stop her menstrual cycle, then the doctor puts her under hormones threatment to estimulate her ovaries to develop follicles. After this step, a HCG is injected at her, so that the doctor can collect the eggs.
The man provide his semen after ejaculating in a dispenser. The physicians mix the egg and the semen and check if the fertilisation has been successful.
If the result is positive, the embryos are implanted inside of the woman's uterus.
After a few weeks the woman should take a pregancy test to confirm the pregnancy.
What would most likely be the outcome to planar cell polarity if calcium were removed from the tissue?
Answer:
If calcium were removed from the tissue then the polarity will be established within the cell but polarity will be lost in the tissue.
Explanation:
Cell polarity is the cellular components like cytoplasm, plasma membranes and other various cell organelles in the asymmetric order. The coordinated arrangement of this cell polarity in tissue plane is called as planar cell polarity (PCP). Calcium is the major component in the tissues that helps in formation of bones and other parts of body, if it is removed then the polarity will not be seen in the tissue, but in the cell the polarity will be established.Motor neurons release the neurotransmitter acetylcholine (ACh) and acetylcholinesterase degrades ACh in the synapse. If a neurophysiologist applies onchidal (a naturally occurring acetylcholinesterase inhibitor produced by the mollusk Onchidella binneyi) to a synapse, what would you expect to happen?
The question is incomplete. The complete question is:
Motor neurons release the neurotransmitter acetylcholine (ACh) and acetylcholinesterase degrades ACh in the synapse. If a neurophysiologist applies onchidal (a naturally occurring acetylcholinesterase inhibitor produced by the mollusk Onchidella binneyi) to a synapse, what would you expect to happen?
A) paralysis of muscle tissue
B) convulsions due to constant muscle stimulation
C) decrease in the frequency of action potentials
D) no effect
Answer:
B. convulsions due to constant muscle stimulation
Explanation:
In response to an action potential, acetylcholine released at the neuromuscular junction or synapse. The release of acetylcholine is followed by its binding to the receptors in the motor endplate and finally triggering a muscle action potential which in turn leads to muscle contraction. Termination of activity of acetylcholine (Ach) is mediated by acetylcholinesterase which destroys ACh and thereby prevents firing of another muscle action potential.
If acetylcholinesterase inhibitor is administered to a synapse, acetylcholine will keep on triggering the muscle action potential causing continuous muscle contraction and irregular body movements (convulsions).
Homologous structures (Group of answer choices):
A. are also called analogous structures.
B. have identical functions.
C. are shared by organisms of the same genus.
D. have fully divergent functions.
E. are often shared by organisms in the same line of descent.
In garden peas, the yellow seed trait is dominant over green seeds. Also, the round seed trait is dominant over the wrinkled-seed trait. These genes are on separate chromosomes. Suppose that two plants that are heterozygous for both traits are crossed and 720 offspring are produced. About how many progeny will be yellow with round seeds?Select one:
a. 405
b. 180
c. 360
d. 60
e. 540
Answer:
405
Explanation:
Gregor Mendel worked with pea plant and observed the inheritance of seed colour and shape in the plant. This is a dihybrid cross involving two genes; one coding for seed colour and the other for seed shape. The allele for yellow seed (Y) is dominant over green (y) in the first gene, while the allele for round seed (R) is dominant over wrinkled seed (r) in the second gene.
When Mendel crossed truebreeds i.e. homozygous parents, he got a F1 generation which is heterozygous for both traits (YyRr). He crossed two heterozygous plants, and according to the law of independent assortment, four possible chromosome combinations of gametes were produced viz: YR, Yr, yR, yr.
Mendel discovered that from a cross involving two hybrid genes, 16 variations were possible. In the genetic make-up, the kinds of F2 offsprings possible from this dihybrid cross are; Yellow round, Yellow wrinkled, Green round and Green wrinkled in a theoretical ratio 9:3:3:1 respectively.
According to the question, 720 offsprings were produced. Therefore, to get the number of progeny with yellow round seeds, the ratio will be used.
The ratio of yellow round seeds in Mendel's dihybrid cross is 9/16, hence, among 720 offsprings, we will have about- 9/16 × 720 = 405 pea plants with yellow and round seeds.
Final answer:
Approximately 405 out of 720 offspring from a dihybrid cross of heterozygous garden pea plants (for yellow and round seed traits) are expected to exhibit both dominant yellow and round seed traits, based on the 9:3:3:1 Mendelian phenotypic ratio.
Explanation:
In the scenario where garden peas that are heterozygous for both yellow seed (dominant) and round seed (dominant) traits are crossed, we are looking at a dihybrid cross. Based on the principles of Mendelian genetics, we can predict the phenotypic ratios of the offspring's traits. For such a cross, the phenotypic ratio is typically 9:3:3:1 for the combinations of the two traits when both parents are heterozygous.
When we have a dihybrid cross (RrYy × RrYy), the proportion of offspring that are expected to express both dominant traits (yellow and round seeds) is 9/16. Given that 720 offspring are produced, we calculate the number expected to have yellow and round seeds by multiplying the total number of offspring by the expected proportion:
(9/16) × 720 = 405
Thus, the correct answer is option (a), which is approximately 405 progeny with yellow and round seeds.
An advantage of gas exchange in fresh water, compared with gas exchange in air, is that _____.
a. water usually contains a higher concentration of oxygen than air
b. ventilation requires less energy in water
c. the respiratory surface does not have to be as extensive in water
d. water is easier to move over the respiratory surface
e. water loss through evaporation across the respiratory surface can be minimized
Final answer:
Water loss through evaporation is minimized during gas exchange in fresh water, which is advantageous for aquatic organisms. They use gills to facilitate the diffusion of oxygen from water to their bloodstream or coelomic fluid, ensuring efficient gas exchange even though oxygen's concentration is lower in water than in air.
Explanation:
An advantage of gas exchange in fresh water, compared with gas exchange in air, is that water loss through evaporation across the respiratory surface can be minimized. This is significant because, unlike the air environment, organisms living in water do not face the challenge of keeping their respiratory surfaces moist to facilitate diffusion. In aquatic environments, oxygen dissolves in water but at a lower concentration than in the air. Freshwater organisms like fish utilize gills, which are thin, highly branched, and folded tissue filaments that provide a large surface area for the diffusion of oxygen into the bloodstream or coelomic fluid, depending on the organism.
Gas exchange in water involves the movement of oxygen from areas of higher concentration in the water to areas of lower concentration in the blood or coelomic fluid. The water passing over the gills allows aquatic organisms to take up the dissolved oxygen needed for survival, and the gills ensure this process is efficient despite the comparatively lower concentration of oxygen in water.
You have learned that the fusion of egg and sperm produces a zygote. But how does the sperm reach the egg, and how does the zygote develop into a seed, which eventually germinates and grows into a mature sporophyte? In this activity, you will demonstrate your understanding of double fertilization and seed development in angiosperms.
Drag the statements to their appropriate locations on the flowchart of pollination, fertilization, and seed development.
a. pollen tube grows down the style
b. generative, cell divides, forming 2 sperm
c. 2 sperm are discharged into the female gametophyte
d. sperm fuse with the egg & 2 polar nuclei
e. zygote forms & divides into a terminal cell & a basal cell
f. cells of the embryo differentiate into three tissue types
Answer:
Pollination: a. pollen tubes grow down the style.
Fertilization: c. 2 sperm are discharged into the female gametophyte.
d. sperm fuse with the egg & 2 polar nuclei
Seed development: b. generative, cell divides, forming 2 sperm.
e. zygote forms & divides into a terminal cell & a basal cell
f. cells of the embryo differentiate into three tissue types
Explanation:
Fertilization is the fusion of one or more sperm with an egg or the female gametophyte in the case of vegetables as option C and D describes.
Pollination is the process that flower plants use to reproduce with the help of insects that transport pollen from one flower to other depositing it in the pollen tubes that grow down the style in order to connect with the ovary of the flower as option A describes.
As regards seed development once that the fertilization is finished the seed starts to grow as option E and F describes. Option B describes the development of sperms, this process occurs before fertilization and through mitosis and meiosis.