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3 years ago

Define crop rotation.

Biology

2 answers:

Juli2301 [7.4K]3 years ago

8 0

Answer:

Crop rotation is the method of growing a series of different types of crops in the same area across a sequence of growing seasons (China does this). It reduces dependence on just one type of nutrients, it also helps control pests and weeds by the plants developing a resistance all at once.

Lesechka [4]3 years ago

5 0

Answer:

it is a system of farming in which different types of crops are cultivated in a different plot of land on the same farm in a definite order or sequence.

Explanation:

(that is ,the farm is divided into plots and different crops are grown on each plot of land in definite order) this also helps to preserve the fertility of the soil .

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Explain how a mutation that changes the amino acid sequence of the protein hemoglobin affects the protein and results in sickle

Montano1993 [528]

Answer:

sickle cell anemia is caused by a mutation in the hemoglobin beta (or HBB) gene and it leads to a single change in amino acid sequence. this gene is located on chromosome 19

Explanation:

4 0

3 years ago

Very low concentrations of detergent make membranes leaky to small molecules and ions without damaging proteins. In isolated mit

Grace [21]

Options

A. Yes, because all enzymes and electron carriers are functional

B. No, because with a leaky membrane, the proton gradient cannot be maintained

C. No, because leaky membranes inhibit glycolysis

D. No, because leaky membranes do not allow NADH and FADH2 to donate their electrons to the electron transport chain

Answer:

B. No, because with a leaky membrane, the proton gradient cannot be maintained

Explanation:

The proton motive force (PMF) provides the needed pump to generate electrochemical gradients of proton needed for continue influx into the matix of the mitochondria. The proton Influx generates the energy needed by protein ATPase Synthase for synthesis of ATPs by adding inorganic phosphate to ADP to give ATP.

ADP + Pi -----------→ ATP.

If the mitochondria;l intramembrane leaks, then the PMF can not be sustained, therefore electtrochermical gradient which supplies the energy for ATP synthase for ATP synthesis will not be available. Therefore ATP synthesis stops.

5 0

4 years ago

What does monomer need in its structure to undergo addition polymerisation

MA_775_DIABLO [31]

The monomer must be able to form stable covalent chemical bonds between units in order to polymerize.

4 0

3 years ago

imagine a cell-surface receptor protein is being newly synthesized. How can it get into the membrane that it will ultimately be

motikmotik

Answer:

the steps for a new receptor synthesis:

Explanation:

Do not forget the steps vary from an eukarityc cell to prokarityc one.

IN AN EUKARYOTIC CELL:

1- Transcription: in the nucleus, mRNA is synthesized from the DNA sequence that codifies the protein. Exons are spliced if needed by spliceosomes.

2- From nucleus into cytoplasm: mRNA goes through nuclear membrane into the cytoplasm were ribosomes, substrates for protein synthesis and other organelles are.

3- Ribosomes recognize a signal in mRNA and start reading the genetic code, three consecutive nucleotides at a time and adjust the correspondent tRNAs (tRNAs carry the aminoacids)

4- Peptide bonds are formed between consecutives aminoacids, and a polypeptide is build up according to the mRNA sequence.

5- (The mRNA has a signal that is recognized by the rough endoplasmic reticulum) The peptide goes into this reticulum (RER) and then into Golgi apparatus. (more chemical modifications are made if needed). By this moment the protein has an inserted portion in a lipid membrane.

6- The protein is transported in a vessel that finally fusions with cytoplasmic membrane and the receptor is in destiny. Hydrophobic aminoacid sequences are inserted in membrane.

IN A PROKARYTIC CELL:

1- Transcription (no splicing is needed, there are not exons)

2- There are not nucleus and cytoplasm divided (no transport)

3- Ribosomes recognize a signal in mRNA and start reading the genetic code, three consecutive nucleotides at a time and adjust the correspondent tRNAs (tRNAs carry the aminoacids)

4- Peptide bonds are formed between consecutives aminoacids, and a polypeptide is build up according to the mRNA sequence.

5- The mRNA has a signal that is guides the growing protein to cellular membrane. Hydrophobic aminoacid sequences are inserted in membrane.

8 0

3 years ago

What type of dating method would help you determine which layer is oldest? Explain.

Evgesh-ka [11]

The Law of Superposition.

The Law of Superposition states that each layer is younger than the one beneath it.

4 0

3 years ago