MDCAT Biology chapter 1: Biology · Acellular life MCQs with answers
By Team Megalecture · Updated 4 Nov 2026
26 exam-style questions on Biology · Acellular life, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.
Ten Biology · Acellular life questions with answers
Try each one, then open the answer. These ten stay the same; the test draws new ones every time.
1. In the name AIDS (acquired immune deficiency syndrome), the word "acquired" means that the disease
A
is inherited from a parent through a faulty gene
B
is caught by infection during life, not inherited
C
appears only in old age as immunity weakens
D
is caused by a lack of a vitamin in the diet
Show answer
Answer: B. AIDS follows infection with HIV picked up during a person's life; it is not an inherited immune deficiency. Even a baby who catches HIV from its mother has acquired it by infection.
2. The capsid of a virus is built from many smaller protein subunits. Each of these subunits is called a
A
virion
B
prophage
C
nucleocapsid
D
capsomere
Show answer
Answer: D. Capsomeres are the protein subunits that together make up the capsid. The nucleocapsid is the capsid together with the nucleic acid it encloses, a virion is the whole infective particle, and a prophage is phage DNA inserted into a bacterial chromosome.
3. Viruses are described as acellular because a virus
A
has ribosomes and a rigid cell wall but no true nucleus
B
has both DNA and RNA but no cell wall around them
C
has no cytoplasm, ribosomes or metabolism of its own
D
has a nucleus but no mitochondria or plastids
Show answer
Answer: C. A virus is only nucleic acid inside a protein coat (sometimes with an envelope); with no cytoplasm, ribosomes or metabolism of its own, it is not a cell. Ribosomes and a cell wall without a nucleus describe a bacterium, which is a true cell.
4. Poliovirus is best described as
A
a plant virus with DNA and a helical capsid
B
an animal virus with RNA and a polyhedral capsid
C
a bacterial virus with RNA and a complex capsid
D
an animal virus with DNA and a helical capsid
Show answer
Answer: B. Poliovirus infects humans and has single-stranded RNA inside a small polyhedral capsid with no envelope. A helical capsid is typical of tobacco mosaic virus, and a complex capsid of T4 phage.
5. At its point of attachment, a T4 phage digests a small hole in the bacterial cell wall with the enzyme
A
lysozyme
B
reverse transcriptase
C
DNA ligase
D
RNA polymerase
Show answer
Answer: A. Lysozyme released by the phage weakens the cell wall at the point of contact, so the tail core can pass through and the DNA can be injected. Reverse transcriptase belongs to retroviruses such as HIV.
6. During the lytic cycle, the proteins of the new phage heads and tails are made by
A
ribosomes carried inside the phage head
B
the ribosomes of the host bacterium
C
enzymes stored in the phage tail fibres
D
the reverse transcriptase of the phage
Show answer
Answer: B. A phage has no ribosomes; its DNA takes over the host cell, and the host's ribosomes, enzymes, ATP and amino acids are used to make phage proteins. This is why viruses can multiply only inside living cells.
7. The DNA copy of the HIV genome that becomes inserted into a chromosome of the host cell is called a
A
provirus
B
prophage
C
plasmid
D
capsomere
Show answer
Answer: A. The integrated DNA of HIV is a provirus; it is copied along with the host DNA and can later direct the making of new viruses. Prophage is the matching term for phage DNA inside a bacterium.
8. The outer envelope of an enveloped virus, such as the influenza virus, is
A
a piece of host cell membrane with viral glycoproteins in it
B
a second protein capsid of capsomeres outside the first one
C
a peptidoglycan wall that the virus makes with its own enzymes
D
a polysaccharide capsule like the capsule of many bacteria
Show answer
Answer: A. As an enveloped virus buds out of its host cell, it wraps itself in a piece of the host membrane into which viral glycoproteins (spikes) have been inserted. The capsid lies inside the envelope, and viruses have no enzymes for building cell walls.
9. Tobacco mosaic virus is a rod-shaped plant virus. The symmetry of its capsid is
A
polyhedral
B
complex
C
bilateral
D
helical
Show answer
Answer: D. In TMV the capsomeres are arranged in a spiral around the RNA, forming a rod with helical symmetry. Polyhedral capsids, as in poliovirus, look roughly spherical; complex capsids, as in T4 phage, have a head and a tail.
10. Which sequence gives the stages of the lytic cycle of a bacteriophage in the correct order?
Answer: B. The phage attaches and injects its DNA; the DNA is replicated and phage proteins are made; new phages are assembled; finally the cell bursts (lysis). New phages cannot be assembled before their DNA and proteins have been made.
26, each with the answer and a short explanation, across 2 topics: Viruses: structure and classification, Viral replication and disease. Every chapter test draws ten of them, so you can take it many times.
Is the MDCAT Biology chapter 1 test free?
Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.
How is the chapter test marked?
The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.
