The xylem cells are square, whereas the phloem cells are round. From which part of the stem tissue is wood made? Select one: a. spongy mesophyll b. the cuticle c. old layers of xylem and phloem d. central parenchyma Flat leaves lose water to the environment more readily than pine needles do.

Final answer:

Phytoplankton are the most important primary producers in the marine aquatic food web, performing most of the ocean's photosynthesis and supporting the food web as the main food source for zooplankton, the primary consumers.

Explanation:

The most important primary producers in the marine aquatic food web are phytoplankton. Phytoplankton can be found floating on or near the surface of the water where sunlight can penetrate, and they perform the bulk of the ocean's photosynthesis, contributing to 95% of the ocean's primary productivity. These organisms can typically be found up to the depth where light can still reach, which is known as the euphotic or photic zone.

This zone can extend to depths of about 200 meters but varies depending on water clarity. Phytoplankton serve as the foundation of the marine food web, feeding zooplankton which represent the primary consumer level, followed by secondary consumers such as small fish.

Phytoplankton play a crucial role in both aquatic and terrestrial environments as they are significant consumers of carbon dioxide (CO2) and producers of oxygen through the process of photosynthesis. Their abundance and health are thus critical for marine ecosystems and global carbon cycles.

Answer: Population

All the newts in the pond best describes population

Explanation:

Population is the total number of organisms of the same species living together in a given area at a particular time. In an ecosystem, the community is made up of many populations of different species of organisms relating with their environment.

Therefore, of all the different species of organisms present in the pond, the newts alone best describes a population

Answer: Option C.

It describes population.

Explanation:

Population is the sum total of living organisms of the same species that live in a particular geographical area, interacting with each other and are capable of interbreeding. The newts in the pond is described as population. Because there are many number of newts that are living and interbreeding in the ponds.

Answer: Option C.

It is called internal respiration.

Explanation:

Respiration is the process of inhaling oxygen from the outside environment and exhaling carbon dioxide ,which lead to the release of energy.

Respiration can be divided into internal , external, ventilation and cellular respiration.

Internal respiration or peripheral gas exchange occurs in the tissue where oxygen moves out of the blood and carbon dioxide is transported out of the cells.

External respiration occurs in the lungs where oxygen move into the blood and carbon dioxide diffuses into the alveolar air.

Internal respiration is the gas exchange that occurs at the level of the tissues. It involves the release of oxygen and pickup of carbon dioxide within the body tissues, occurring via simple diffusion without the need for energy. Option (c) is correct.

The gas exchange that occurs at the level of the tissues is called internal respiration. This is the process where oxygen is released and carbon dioxide is picked up within the body tissues. This process alongside external respiration, which occurs in the alveoli of the lungs, forms an integral part of the respiratory system. While external respiration refers to the exchange of gases with the external environment, internal respiration refers to the exchange of gases with the internal environment.

These exchanges occur due to simple diffusion, following pressure gradients, without need for energy to move the gases across membranes. The anatomy of the lungs with its thin respiratory and blood capillary membranes, as well as large surface area, maximizes this diffusion process, thus promoting efficient gas exchange.

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Answer:

b. 72%

Explanation:

Survival rate of underside of branches & topside of branches resurrection ferns are equal. Let say p + q = 1

Resurrection ferns that grow on the underside of branches receive less water than those growing on the topside and, therefore, have a fitness of only 0.28

That shows and indicate that they vary in reproducing factor.

let the reproducing factor be (p) = 0.28

let the no-reproducing factor be (q) = ???

0.28 + q = 1

q = 1 - 0.28

q = 0.72

q = 72 %

These have been sorted here:

The SMC (structural maintenance of chromosomes) proteins encompass two major complexes in eukaryotes: cohesins and condensins.

Cohesins maintain sister chromatid cohesion after replication until separation, associated with kleisin, and crucial for DNA replication and cell division.

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Final answer:

Cohesins and condensins are SMC protein complexes essential for chromosome maintenance in cell division. Cohesins primarily hold sister chromatids together, while condensins contribute to chromosome compaction during mitosis. Both share structural features and are crucial for DNA replication and cell division.

Explanation:

The SMC (structural maintenance of chromosomes) proteins are crucial for the proper regulation of chromosome structure and segregation during cell division. Specifically, in eukaryotes, cohesins and condensins are two major complexes involved in chromosome maintenance. The function and structure of these complexes can be described by the following phrases:

Answer:

Final answer:

Two bands would be observed after isolation and ultracentrifugation of DNA from the Meselson and Stahl experiment following two generations in 14N: one intermediate density band (indicative of one 15N and one 14N strand) and one light density band (indicative of double 14N strands), proving semiconservative DNA replication.

Explanation:

In the Meselson and Stahl experiment which aimed to understand the mechanism of DNA replication, they observed the effects of consecutive generations of bacterial growth in media with different nitrogen isotopes. Initially, E. coli was grown in a heavy nitrogen isotope, 15N, followed by growth in a lighter isotope, 14N. After two generations in 14N, when the DNA was isolated and subjected to density gradient ultracentrifugation, two bands were observed. One band was of intermediate density, indicating it contained one 15N-labeled strand and one 14N-labeled strand. The second band was of lighter density, corresponding to DNA composed solely of 14N-labeled strands. This provided strong evidence for the semiconservative model of replication where each daughter DNA molecule consists of one parental and one new strand.

Answer: The viral DNA has a sharp thermal transition.

Explanation:

Due to more guanine to cytosine (G-C) bonds in viral DNA, and the extra stability its presence confers, the double stranded Viral DNA is more stable to heat and have a higher melting point.

Hence, even when denatured by heat, the unstacked base pairs in its single strands only absorb ultraviolet light at a minimal rate such as 10% increase or less, before it gets renatured into double stranded DNA again.

Thus, the ability of viral DNA to adjust to thermal (heat) denaturation is the reason.

The low absorbance increase at the melting temperature suggests that the structure of the viral DNA may be more resistant to the heating process, which could mean it has a more complex or compact form than typical DNA.

The UV light absorption data suggests that the newly discovered viral DNA has a unique structure differing from typical DNA. When DNA is heated to its melting temperature, the two strands 'unzip' or separate, leading to an increase in absorbance. A typical increase in absorbance at the melting temperature for ordinary DNA is around 37%. In this case, the increase was only 10%, indicative that the structure may be more resistant to the heating process, perhaps due to additional base-pairing or tighter coils. This suggests that the viral DNA might have a more complex or compact structure compared to typical DNA.

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Answer: True

Explanation:

Enzymes are biological molecules or proteins that speed up chemical reactions or processes in living cells but do not get used up and can be use over again.

Enzymes are very important in the body in that they help in digestion( I.e breakdown of food particles into small pieces) and metabolism. They change energy requiring actions to energy releasing reactions.

The statement that "enzymes are proteins that change energy-requiring reactions to energy-releasing reactions" is false.

Enzymes are proteins that act as biological catalysts to speed up both energy-requiring and energy-releasing reactions by lowering the activation energy, but do not change the type of reaction.

Enzymes are indeed proteins, but they do not change the type of reaction. Instead, they function as biological catalysts to speed up chemical reactions, including both energy-requiring (endergonic) and energy-releasing (exergonic) reactions. They achieve this by lowering the activation energy needed for reactions to proceed.

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Answer:

b. Design a test for identifying heterozygous carriers of the allele.

Answer:

A scientist discovers a DNA-based test for one allele of a particular gene. This and only this allele, if homozygous, produces an effect that results in death at or about the time of birth. Which of the following statements describes the best use of this discovery?

Screen all newborns of an at-risk population.

Explanation:

When all newborns are screened, it enable the researcher to identify areas with lapses   in order to correct such either by introducing an heterozygous to correct the abnormality

Answer:

The seafloor is only 180 million years old due to the process of subduction. The floor of the sea's tends to get colder and denser with the passage of time. At a certain time, the seafloor becomes so dense that it sinks in the upper mantle. The Earth's crust cannot undergo this process and hence has oldest rocks. We can say that the seafloor is less than 180 million years old because it is typically recycled back into the mantle of the Earth.

The oldest sea floor is only 180 million years old because new seafloor is constantly being created through seafloor spreading at mid-ocean ridges.

The reason that the oldest sea floor is only about 180 million years old, while the Earth is 4.6 billion years old, is because new seafloor is constantly being created through a process called seafloor spreading. This process occurs at mid-ocean ridges, where tectonic plates are moving apart.

As the plates separate, magma from the Earth's mantle rises and solidifies, forming new oceanic crust. Over time, this new crust moves away from the ridge and gets older, while new crust forms at the ridge. Therefore, the oldest sea floor is relatively young compared to the age of the Earth.

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Answer:

Major histocompatibility complex

Explanation: In a variety of animals, including humans, there is a correlation between odor preference, and genetic similarity at the Major Histocompatibility Complex (MHC).

MHC is a highly polymorphic group of genes that play an important role in the immunological self/non self recognition. Its products have been recognised to take part on the numerous compounds and reactions that build up an individual's body odor.

Answer: Option A) All types of RNA in the cell are synthesized by transcription, which uses a portion of DNA as a template for copying.

Explanation:

All types of RNA:

- viral RNA,

- ribosomal RNA,

- transfer RNA,

- messenger RNA and

- double-stranded RNA, have a sequence that is the same as 'antisense' strand of the DNA.

Thus, it is true that all types of RNA in the cell are synthesized by transcription, which uses a portion of DNA as a template for copying.

Option A is the correct statement regarding transcription: All types of RNA in the cell are synthesized by transcription using a portion of DNA as a template.

The correct statement concerning transcription is option A: All types of RNA in the cell are synthesized by transcription, which uses a portion of DNA as a template for copying. Transcription is the process by which an RNA molecule is synthesized using a DNA template. Specific sequences called promoters signal the start of a gene, and terminator sequences signal the end of gene transcription, not the other way around as mentioned in option B. The entire chromosome is not copied during transcription; only the specific gene being transcribed is copied.

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Answer with explanation:

Gibson Assembly is a method of molecular cloning which join multiple DNA fragments in a single reaction.  It was created by Daniel G. Gibson, Chief Technology Officer and co-founder of SGI-DNA. (See attached picture)

a. Role of Phusion DNA Polymerase

It bring the enzymes closer to DNA fragment and help enzymes to make PCR product with speed and more accurately. Moreover it has the ability of amplifying long templates. (See attached picture)

a. Role of T5 exonuclease

It is an exonuclease enzyme which means it remove the nucleotide from DNA stand in 5´ to 3´ direction. It create nicks in the double stranded DNA for the incorporation of other fragments. Furthermore, it also work fine in single stranded DNA. (See attached picture)

a. Role of Taq DNA ligase

It is a thermostable enzyme which catalyzes the phosphodiester bond formation between 5´-phosphate and the 3´-hydroxyl of two adjacent DNA strands. (See attached picture)

The rigid structure that supports and envelopes the bacterial cell outside the plasma membrane is the cell wall, primarily composed of peptidoglycan. This provides the cell with strength, maintains its shape, and shields it from environmental threats.

The rigid structure that surrounds and supports the bacterial cell, which is found outside of the plasma membrane, is called the cell wall. Bacterial cell walls are primarily composed of peptidoglycan, a large polymer of amino sugars. These sugars are linked together in a mesh-like structure providing the cell with strength and rigidity. The cell wall helps maintain the shape of the cell and also protects it from environmental threats such as changes in osmotic pressure.

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The rigid structure found outside the plasma membrane that surrounds and supports the bacterial cell is called the "cell wall."

The cell wall is a crucial component of bacterial cells, providing structural support and protection. It is a tough, rigid layer composed of peptidoglycan, a unique macromolecule that consists of sugar chains cross-linked by short peptides. The cell wall maintains the cell's shape and prevents it from bursting due to changes in osmotic pressure. It also plays a significant role in bacterial pathogenicity, as differences in cell wall structure are used to classify bacteria into two major groups: Gram-positive and Gram-negative.

Gram-positive bacteria have a thick layer of peptidoglycan, while Gram-negative bacteria have a thinner layer of peptidoglycan surrounded by an outer membrane. The cell wall is an essential target for antibiotics like penicillin, which disrupt its integrity and ultimately lead to bacterial cell death.

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C) A and B only  is the right option.

Explanation:

During the process of cell division as mitosis or meiosis, the random segregation of mitochondria takes place in the resulting daughter cells

It is found that when cell divides, mitochondria present on the opposite side of the cell plate will have daughter cells that are different from the progenitor cell with respect to  mitochondria. Due to this reason, it is difficult to predict the percentage of mitochondrial mutation passed on.

Also, it is proved that only maternal cells are capable of passing the mitochondrial DNA.

Final answer:

Mutated mitochondria are distributed randomly during cell division, leading to varying percentages in daughter cells.

Explanation:

When a mutation arises on the mitochondrial genome and 10% of the mitochondria in a cell have that mutation during cytokinesis, the distribution of the mutated mitochondria will be random in the daughter cells. Since mitochondria divide independently and are distributed randomly during cell division, there is no precise mechanism to ensure equal distribution of mutated mitochondria. Therefore, the percentage of mitochondria with the mutation in the two daughter cells will vary and could differ from the initial 10%.

Answer:

These statements refer to various mechanisms that act as a reproductive or hybridization barriers.

In nature there are different mechanisms that prevent the crossbreeding between different species, what in biology is called reproductive barriers. Some mechanisms that act by preventing hybridization between different species are:

These mechanisms are responsible for preserving the genetic integrity of each species by preventing hybridization between different species.

Explanation:

This is accurate. Horses and donkeys belong to two different species, with a different chromosomal load:

Both species can be bred, but their descendant, mules (Equus africanus x ferus), have an odd number of chromosomes (63) and are infertile. This represents an exact example of hybrid breakdown.

This is not accurate. In sponges, like some coral species, periods of release of gametes and fertilization vary throughout the day, with some synchrony between individuals of the same species.

The fact that some sponges release their gametes by day and other species do it at night is an example of the reproductive barrier called temporal isolation.

This is accurate. When two related but different species - such as turtles - have their mating period at different times of the year, there is talk of temporal or seasonal isolation.

Temporal isolation is a reproductive barrier that prevents crossing between different species, due to their mating habits at different times.

This statement is accurate. In the case of sea urchins, the encounter of gametes requires two chemical mechanisms:  

These two chemical mechanisms ensure that gametes of two different species cannot be joined and fertilized, which is an example of gametic isolation.

This is accurate. The sensitivity to the touch of damselflies is specific to individuals of the same species, preventing mating between male and female of different species.

This, like courtship, is a mechanism that prevents crossbreeding between different species, establishing an example of mechanical isolation.

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Answer:

The answer is D

Number of motor units recruited

Explanation:

The force a muscle generates is dependent on the length of the muscle and its velocity which is shortened.

A motor unit is the grouping of muscle fibers supplying nerves by the neuron and consists of the motor neuron.

The number of muscle fibers within a motor unit varies, and is a function of the muscle’s ability for accurate and refined motion.

Precision can be determined to be inversely proportional to the size of the motor unit. As a result, small motor units can exercise greater precision of movement compared to larger motor units. For example, thigh muscles which are responsible for large powerful movements, can have a thousand fibers in each unit, while eye muscles which requires small precise movements, might only have about ten.

Groups of motor units are supplied with nerves to coordinate contraction of a whole muscle and generate appropriate movement; all of the motor units within a muscle are referred to as a motor pool.

As a result, the number of motor units with are recruited will facilitate the maximum amount of tension that allows the student keep his arm extended in place under the  increasing weight of the books.

Answer

D.Osteoblasts

Explanation:

Appositional growth is the increase in the diameter of bones by the addition of bony tissue at the surface of bones. Osteoblasts at the bone surface secrete bone matrix, and osteoclasts on the inner surface break down bone. The osteoblasts differentiate into osteocytes.

The cell responsible for secreting the matrix of bone is the osteoblast, which supports the growth, maintenance, and repair of bones.

The cell responsible for secreting the matrix of bone is the osteoblast. Osteoblasts are a type of bone cell that form new bone, or 'osteo', tissue. They do this by secreting a matrix that later mineralizes to become hardened bone tissue. This process is critical for the growth, maintenance, and repair of bones in the body.

In contrast, osteoclasts are involved primarily in the breakdown and resorption of bone tissue, while chondroblasts and chondrocytes are associated with cartilage formation and maintenance, not with bone tissue formation.

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Answer:

Synaptic cleft

Explanation:

Synaptic cleft is the gap between the terminal end of the presynaptic cell and the terminal end of the postsynaptic cell. It helps in transportation the neurotransmitters from a synapse to another.

Answer:

The horse has 64 number of chromosomes and the donkey has 62 number of chromosomes.

At the time of recombination the number of chromosomes which will be formed will be odd in number.

32 from horse and 31 from donkey which combines to form 63 pair. This is a odd number so there can be no equal number of segregation of chromosomes.

This is the fact the offspring produced by crossing a donkey and horse is sterile.

The procedure and conditions under which photosynthesis is conducted can affect the outcome and changes in the outcome may indicate alterations in the net rate of photosynthesis. Several factors related to the procedure, such as light intensity, temperature, carbon dioxide concentration, water availability, chlorophyll content, and duration of the experiment, can impact the outcome. Researchers often conduct controlled experiments to understand the specific factors influencing photosynthesis.

The procedure and conditions under which photosynthesis is conducted can indeed affect the outcome, and changes in the outcome may indicate alterations in the net rate of photosynthesis. Photosynthesis is a complex process that involves several factors, and variations in the experimental setup can influence its efficiency.

Here are a few factors related to the procedure that can impact the outcome:

If the outcome changes, it may indicate a difference in the net rate of photosynthesis. An increase in the outcome might suggest an enhancement in photosynthetic activity, while a decrease could indicate a reduction. Researchers often conduct controlled experiments, adjusting one variable at a time while keeping others constant, to understand the specific factors influencing photosynthesis.

Answer:

Food could not reach the stomach without the "esophagus and the throat".

Explanation:

Esophagus is like an elastic pipe, about 25 cm in length. It passes food from the throat back towards the stomach. There's the trachea at the back of the mouth which enables air to come in and out of the body. Once food in the form of a small ball of mushed-up food or liquids is ingested, the epiglottis slips down the opening of the windpipe to ensure that the food reaches the esophagus and not the windpipe.

Food is transported to the stomach via the esophagus with the help of the pharynx through peristalsis. Once in the stomach, food is stored, chemically digested, and mechanically broken down into chyme before moving into the small intestine.

Food couldn't reach the stomach without the involvement of the esophagus and the pharynx. The esophagus is a muscular tube that connects the pharynx to the stomach, and its main function is to transport food from the throat down into the stomach. The pharynx, also part of the digestive tract, is the area at the back of the throat that receives food from the mouth. Together, the coordinated contractions of these structures move food along in a process called peristalsis. After passing through the esophagus, the food reaches the stomach, where it is stored and chemical digestion begins in earnest, starting with the conversion of food into a semi-liquid mixture called chyme. The stomach's muscular movements help in further breaking down the food before it enters the small intestine for continued digestion and absorption.

Answer:

Option B

Explanation:

Failing of right side is usually caused by failure of left side of heart. Malfunctioned right side of the heart loses its power of efficient pumping and as a result of this the blood is pumped back into the lungs. This backward flow backs up in the veins thereby causing the fluid to swell and hence the swelling in various body parts such as legs, liver, GI tracts, abdomen etc.

Hence, option B is correct

Answer: Option B.

Explanation:

Pulmonary infection is also lung infection. It can be caused by virus, bacteria or fungi.

A person can be infected when he breathing the pathogens from the air. A person with pulmonary infection can have right sided heart failure.

Right sided heart failure occur when because of left sided heart failure. The left sided failure occur when the left ventricle loses power to pump blood to the rest of the body. As a result, blood is pump to the lungs which weaken the right side of the heart and this lead to right side heart failure.

Answer: Cells are the simplest structure to fit all of the characteristics necessary to be considered alive.

Explanation:

The cell is regarded as the smallest unit of all living things because it can carry out all life activities such as:

- feeding

- reproduction

- excretion

- growth

- adaptation

- respiration

- definite life span

- sensitivity, and

- movement

All these characteristics possessed by cells are the characteristics of living things.

Answer: Cells are the simplest structure to fit all the characteristics to necessary to be considered alive.

Explanation:

Cell is the smallest and basic units of life I.e it is the building blocks of living organisms. Cells can exist on their own. Cells are the smallest unit of life because they are the smallest components of living organisms and have simplest structure to fit characteristics to be considered alive.

These characteristics are exhibited by living cells and they are;

Reproduction, feeding,respiration, movement, sensitivity, excretion ,growth and death.

Answer:

a. they integrate activity within a single brain structure.

Explanation:

This can be local interneurons and relay interneuron based on function and structure.

Based on  function the interneuron synapse with the  sensory and motor neurons,This structural characteristic is related to their functions. Thus as sensory neurons synapse with the Interneurones,  the recieved message from sensory neuron of the spinal cord  first branched off to the brain for processing and analysis, and  output (response) from the brain returns to the interneuron , which synapse this with the motor neurons, for transmission to the effectors.

This  type of information integration  and processing is especially important when processing information from high brain centers, and  complex tasks,and it involved the relay interneuron. This explains  the integration function  within the brain structure.

However if the information is simple the local interneuron mediated this/ a sensory information is not sent to the brain. Rather the information is transmitted from the sensory to the motor , coordinated by the spinal cord and response is transmitted to the effectors.

Answer: Polygenic inheritance

Explanation:

Polygenic inheritance is a phenomenon that explains how a character like skin color show a range of more or less continuous variation due to many genes controlling it. And this is unlike Mendel traits that are controlled by single genes.

So, skin color in an individual is expressed as red hair and pale skin.

Answer:

Option d, a fossil used to categorize a stratigraphic layer

Explanation:

Fossils that are typical of a specific time range in the course of history of evolution of earth are generally termed as index fossil.  These fossils can be used to determine the age of the rock layers and fossils with in which they are found. An index fossil must have a unique identity so that it can be easily recognized.Along with this they must have a lived for a short span of time in horizontal rock layer which must be geographically widespread for matching up to huge distances.  

Hence, option D is correct

Answer:

Option (D)

Explanation:

An index fossil is usually defined as those fossil that appeared for a short geological time and were widely distributed over the surface of the earth. These fossils are extremely rare, and it plays an important role in determining the age of a rock, and it also helps in the correlation of rocks. A noticeable number of index fossil species were observed in different places on earth which were deposited on the rock sequences in the geological time.

It enables a geologist to categorize the different stratigraphic layers.

Thus, the correct answer is option (D).

Answer:

A, B, and D

Explanation:

Answer:

Victoria will intially felt active, reduced sleepiness but consuming too much caffeine may be risky.

Explanation:

Victoria will felt more active and alert after 30-45 minutes of drinking the enrergy drink because energy drink contains caffeine and its concentration in at peak after 30-45 minutes. Caffeine will reduce sleepiness.

Caffeine will block the adenosine pathway for short period of time. Adenosine is a chemical becuase of which we felt tired and Caffeine will allow feel good molecules to be released in brain such as dopamine. That why Victoria will felt more active, concentrated and good.