Levene made which contribution to our understanding of DNA structure? a. He determined that the nucleus contains DNA. b. He determined that DNA contains four nitrogenous bases. c. He determined that DNA consists of nucleotides. d. He determined that the nitrogenous bases of DNA are present in regular ratios.

Answers

Answer 1

Answer:

Answer:

The correct answer is b. He determined that DNA contains four nitrogenous bases.

Explanation:

Levene was an American biochemist who studied the structure of DNA in the early 1900s and in 1920 he found that DNA consists of four nitrogenous bases that are Adenine, Guanine, Thymine, Cytosine.

He also found deoxyribose sugar and phosphate group and said that nucleotide is the basic unit of DNA which contains a ribose sugar with attached nitrogenous base and phosphate group.

He also concludes that an equal amount of adenine, guanine, thymine, and cytosine makes the DNA which is now known as tetranucleotide hypothesis. So the correct answer is b. He determined that DNA contains four nitrogenous bases.

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A cell’s relatively constant internal physical and chemical conditions are called __________.A. hemostasis

B. homeostasis

C. osmosis

Answers

B. homeostasis is the term that is used to describe a cell's relatively constant internal physical and chemical conditions.

The cells that are on each side of a stomata and open and close it like a mouth are called _____. guard cells meristem cells parenchyma cells collenchyma cells

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The cells that are on each side of the stomatal pore and open and closeit like a mouth is called guard cells. Guard cells are found almost allover the body part of the plant. The opening and closing of the stomata acts asa mediator by changes in turgor pressure of the guard cells. Turgor pressurepushes and sometimes out of the cell wall of the plant to allow ions ofsolution to come in and out. The stomatal pore of the guard cell becomes largewhen water is present around it and it is small when water is not present.

Answer:

The cells that are on each side of a stomata and open and close it like a mouth are called guard cells.

The inability to start a pregnancy after having unprotected vaginal intercourse for more than a year or the inability to stay pregnant for the full length of a normal pregnancy is?

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The given condition is termed as Infertility.

The infertility can be defined as the condition, in which the woman is not able to produce the young ones. This condition can be characterised by the absence of pregnancy, when no protection is used during intercourse or not able to stay pregnant. This condition can be a result of the fault in the reproductive system of the woman.

The inability to start a pregnancy after having unprotected vaginal intercourse for more than a year or the inability to stay pregnant for the full lengthof a normal pregnancy is called infertility. I hope that this is the answer that you were looking for and it has actually come to your help.

What characteristics separate algae from a) protozoans and b) plants?

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a.) Algae vs Protozoans

The main difference between Protozoans and Algae is that Algae are autotrophs, meaning they make their own food. Protozoans, on the other hand, are heterotrophs, they ingest other organisms or organic molecules.

b.) Algae vs plants

One of the more striking differences between algae and plants is their complexity. Algae can either be unicellular or multicellular, while plants are multi-cellular only. Plants have vascular systems, it allows the uptake and transport of nutrients and water. Algae needs to get all of its nutrients from water. Reproduction is also another difference between them. Plants have a more complex mode of reproduction. Algae reproduces through spores and replication.

Answer:

a.) Algae vs Protozoans

The main difference between the algae and protozoa is that algae can make their own food by the help of photosynthesis and and protozoa ear the food made by autotrophs.

b.) Algae vs plants

The main difference between the algae and plants is that algae has a simple body structure sometimes they are unicellular and plants are multicellular complex kind of body organization.

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Answer:

Explanation:

I know it is not B) Stabilize

I missed this question

Describe the phases of the moon.

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Answer:

Waxing Cresent ( when the moon is growing in size to reach it's maximum fullness), FIrst Quarter (When the moon is one quarter full), Waxing Gibbous (When the moon is over half full), Full Moon (When the moon is completley full), Waning Gibbous (When the moon is almost half dark), Last Quarter (When the moon is half dark), Waxing Cresent (When the moon is a small cresent shape in the sky), New Moon (When the moon is completley dark)

Explanation:

Hope this helps!! :)

Answer:

Here

Explanation:

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