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3 years ago

Which scientist showed that organisms do not grow spontaneously in beef broth?

Biology

2 answers:

Luden [163]3 years ago

8 0

Answer:

Louis Pasteur

Explanation:

Louis Pasteur designed an experiment in which he proved that life cannot generate or grow spontaneously. It needs some base for taking birth or rebirth.

For instance, in his experiments the flasks that were exposed to the dust have generated cloudy solution but the flask that were unbroken did not show any such sign. Thus , he proved that microbes appeared in broken flask because of the presence of dust.

Hence he showed that that organisms do not grow spontaneously in beef broth

QveST [7]3 years ago

7 0

Answer:

Louis Pasteur.

Explanation:

Louis Pasteur gave theory of spontaneous generation that states, life arose from non-living things. Pasteur disprove the theory of spontaneous generation by S-shaped tube experiment.

He used swan-neck shaped flasks (twisted necks) and filled the flasks with sterilized beef broth. Due to twisted neck, entry of air was allowed to the flasks from outside, but not microorganisms.

In these sterilized flasks, microorganisms could not grow as entry of airborne microbes was prevented. But if the necks of flasks were broken, growth of microorganisms entered into flasks and showed growth.

Thus, Louis Pasteur showed that microorganisms do not grow spontaneously in flasks with beef broth.

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Meiosis Foldable Activity 515.2

Aleksandr-060686 [28]

Explanation:

During the process of prophase I, the nuclear envelope containing chromosomes has only partly broken down homologous chromosomes are joined together by proteins and a complex or pairing call synapsis- corresponding genes on sister chromatids are aligned precisely.

The syanapsis allows for crossing over which is the exchange of segments of chromosome, between non-sister homologous or similar chromatids crossing over happens at chiasmata, the point where non-sister chromosomes are joined.

Further Explanation:

All the genetic information within the eukaryotic cell is stored within the nucleus as helical DNA. This DNA is tightly wound around histones as chromosomes. In meiosis, the number of chromosomes (2n) is halved to 23 chromosomes (haploid number)through meiotic divisions, producing 4 haploid (n) germ cells or gametes (sperm or eggs), each containing half the number of chromosomes as its parent cell.

In Meiosis I

homologs pair off into bivalents
At crossing over: the exchange of segments of chromosome, between non-sister homologous or similar chromatids crossing over happens at chiasmata, the point where non-sister chromosomes are joined in prophase I forming bivalents; tetrads are formed.
Spindle fibers from centrioles join sister chromatids together at their centromeres in metaphase I, pulling them to the equator of the cell;
then, in anaphase I, while joined, they are pulled to opposite sides of the cell; the cell body splits and the nuclear envelope reforms in telophase I

In Meiosis II...

Later, in prophase II, the nuclear envelope disintegrates and mitotic spindle fibers are formed
independent assortment occurs. in metaphase II of meiosis: spindle fibers attach to centromeres, chromatids align independently at the equator. Genes segregate independently into new combinations as sister chromatids are pulled apart by their centromeres in anaphase II
in telophase II the cells' nuclei and membrane are then formed with each containing the haploid number (n)
Following the formation of gametes in the last stage, randomized fertilization occurs in sexual reproduction sperm cells fertilize an ovum to form a zygote. This occurs randomly by chance, to result in a complete set of chromosomes 2n, that is a novel combination of half each parent's number of chromosomes

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2 years ago

Rivers and streams are biodiverse ecosystems that are sensitive to change. please select the best answer from the choices provid

mylen [45]

It is true that rivers and streams are biodiverse ecosystems that are sensitive to change. Details about rivers and streams can be found below.

<h3>What is river and stream?</h3>

A river is a large and often winding stream which drains a land mass, carrying water down from higher areas to a lower point, oftentimes ending in another body of water, such as an ocean or in an inland sea.

On the other hand, a stream is a small river or a body of moving water confined by banks.

Rivers and streams are both freshwater ecosystems, hence, tend to respond to changes in their environment caused by anthropogenic activities.

Therefore, it is true that rivers and streams are biodiverse ecosystems that are sensitive to change.

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dalvyx [7]

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ziro4ka [17]

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