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3 years ago

Which of the following can be used to compare the amount of radioactively

Biology

1 answer:

katovenus [111]3 years ago

6 0

Answer:

D. Scintillation counter

Explanation:

DNA is usually labelled with radioactive phosphorus, which is a β emitter, so you need a device that can detect β particles.

A scintillation counter detects β particles because they emit a flash of light when they hit a phosphor. The device converts the flashes into electrical signals, amplifies then about a million times, and then counts them.

A, B, and C are wrong. They are all common laboratory equipment, but they can't detect radioactivity of any sort.

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Which type of immune system cell engulfs pathogens and other foreign particles?

FromTheMoon [43]

A macrophage is a large phagocytic cell that engulfs foreign particles and pathogens. So Macrophage.

Hope this help! :)

6 0

2 years ago

Is the movement of water along the concentration gradient

Nuetrik [128]

Answer:

<em>- Is the movement of water along the concentration gradient: </em><em>Osmosis</em><em>. </em>

<em>- Is the use of energy to move the particles against the concentration gradient: </em><em>Active transport</em><em>. </em>

<em>- Is the movement of particles by diffusion without energy: </em><em>Simple diffusion</em><em>. </em>

<em>- Is the movement of particles along the concentration gradient: </em><em>Passive transport</em><em>.</em>

Explanation:

The mechanisms of cellular transport involve all the processes that the cell carries out to incorporate substances into its interior or send them to the extracellular space, through its semipermeable cell membrane.

<h3>- Osmosis</h3>

Is a type of transport that consists of the passage of water from a space with a lower concentration of solutes to one with a higher concentration, in order to reach equilibrium, following a concentration gradient.

The concentration gradient is given by the difference in concentration between two substances, which indicates the direction in which molecules, such as water, should move from one place to another.

<h3>- Active transport</h3>

Unlike passive transport mechanisms, which depend on a concentration gradient that determines the movement of particles, in active transport there are two characteristics that define it:

The passage of substances into the cell against a concentration gradient.

The use of energy to carry out this process.

In this case, the passage of substances through the cell membrane will be according to the requirements of the cell, or when they cannot pass through the membrane.

<h3>- Simple diffusion</h3>

According to the characteristics of the cell membrane, some substances can pass freely through it while others require special mechanisms. When a molecule is able to pass through the membrane without the use of special mechanisms or energy we speak of simple diffusion.

In a cell membrane, whose composition is by hydrophobic or non-polar lipid molecules, simple diffusion allows the passage of non-polar molecules, gases and alcohol.

<h3>- Passive transport</h3>

Refers to the mechanism of entry and exit of substances from the cell that does not require the use of energy.

The mechanisms involved in the passive transport of the cell are simple diffusion, osmosis, facilitated diffusion - which requires special conveyors or channels - and ultrafiltration, which depends on hydrostatic pressure. Examples of substances using this mechanism are lipid molecules, water and electrolytes.

Learn more:

Lipidic bilayer and cellular transport brainly.com/question/6955159

3 0

3 years ago

the discovery that chromosomes are involved in inheritance was made possible by the invention of the what?

dexar [7]

Answer:

The Microscope...

7 0

2 years ago

Why is it easy for a virus to mutate?

drek231 [11]

Answer:

Viruses mutate very quickly The major reason that viruses evolve faster than say, mosquitoes or snakes or bed bugs, is because they multiply faster than other organisms. And that means every new individual is an opportunity for new mutations as they make a copy of their genetic material. Many of those mutations have no noticeable effect.

Explanation:

6 0

3 years ago

A gene that affects hair length in dogs has two alleles. The allele for short hair (L) is dominant

Lelechka [254]

Answer:

This question lacks options, the options are:

A. Only recessive alleles are inherited from homozygous parents.

B. Dominant alleles grow weaker as they are passed from parents to offspring.

C. Only the parent with a dominant allele can pass that allele to offspring in sexual reproduction.

D. A heterozygous parent has an equal chance of passing either the dominant allele or the recessive allele to offspring.

The answer is D

Explanation:

This question involves a single gene coding for hair length in dogs. The allele for short hair (S) is dominant over the allele for long hair (s). This means that allele 'S' will always mask the phenotypic expression of allele 's' in a heterozygous state.

According to the question, two heterozygous dogs (Ss) were crossed to produce 6 shortt-haired offsprings and 2 long-haired offsprings. An heterozygous organism is that which contains two different alleles for a particular gene i.e. a combination of dominant and recessive alleles.

Based on this, during meiosis or gamete formation, an heterozygous dog (Ss) will produce gametes with the short hair allele (S) and long hair allele (s) in equal proportion i.e. 50-50. When the two gametes containing the recessive alleles (s) produced by each heterozygous parent fuses, an offspring with a recessive phenotype (long hair, ss) is produced.

Hence, a long-hair

phenotype can appear in the offspring of two short-haired dogs because a heterozygous parent has equal chance of passing either the dominant or recessive allele to the offspring.

6 0

3 years ago