Which describes the missing step?
A. Oxygen is removed from the water bedre step 3,

B. Oxygen is removed from the water after step 3.

C. Tentacles sting and paralyze prey atter step 1

D. Tentacles sting and paralyze prey before step 1

The missing step is oxygen is removed from the water after step 3.

Explanation:

The steps listed by Xavier are:

Porifera or sponges are aquatic, immobile invertebrates whose structure is saccular with an upper opening, the osculus.

Sponges absorb water through their pores, where the porocytes are found, and through flagellated cells -the coanocytes- the movement that allows the entrance of water to the spongocele or atrium is produced, in addition to the phagocytosis of organic elements.

Once the water is in the interior chamber of the sponges, the organic particles are phagocyted to be digested, and the oxygen is removed from the water, and passes through diffusion into the cell.  The waste products, as well as carbon dioxide, are released into the water that will be expelled through the osculus.

In Xavier's list, the missing step is the removal of oxygen from the water, before it is expelled from the body of the sponge.

Learn more:

Sponge structure link

transcription is a process in which information is rewritten. it is something our cells must do, in a more specialized and narrowly defined way. in biology, transcription is the process of copying out the dna sequence of a gene in the similar alphabet of rna. it needs to happen in the nucleus because that's where the dna is. dna is always inside the nucleus unless the cell is dividing.

transcription is the first step in gene expression, which involves copying a gene's dna sequence to make an rna molecule. transcription is performed by rna polymerases. it has three stages: initiation, elongation, and termination. rna molecules must be processed after transcription in eukaryotes.

explanation:

long version:

the protein synthesis consists two processes which are, transcription and translation. transcription takes place in the nucleus. it uses dna as a template to make an rna molecule. rna then leaves the nucleus and goes to a ribosome in the cytoplasm, where translation occurs. transcription is the first part of the central dogma of molecular biology: dna → rna. it is the transfer of genetic instructions in dna to messenger rna (mrna). during transcription, a strand of mrna is made that is complementary to a strand of dna.  

these three stages are:

  initiation: in which   is the beginning of transcription.occuring when the enzyme rna polymerase binds to a region of a gene called the promoter. this signals the dna to unwind so the enzyme can ‘‘read’’ the bases in one of the dna strands. the enzyme is now ready to make a strand of mrna with a complementary sequence of bases.

    elongation: in which is the addition of nucleotides to the mrna strand. rna polymerase reads the unwound dna strand and builds the mrna molecule, using complementary base pairs. there is a brief time during this process when the newly formed rna is bound to the unwound dna. during this process, an adenine (a) in the dna binds to an uracil (u) in the rna.

    termination: in which is the ending of transcription, and occurs when rna polymerase crosses a stop (termination) sequence in the gene. the mrna strand is complete, and it detaches from dna.