Eukaryotic cells are much more complex as compared to prokaryotes. Which one of the following structures is exclusively present in a eukaryotic cell ?
- A.Cell wall
- B.Plasma membrane
- C.Nucleic acid
- D.Mitochondria
Correct answer
Explanation
The correct answer is D, Mitochondria. Mitochondria are membrane-bound organelles, and only eukaryotic cells have membrane-bound organelles.
Prokaryotes such as bacteria and cyanobacteria have no true nucleus and no membrane-bound organelles; their DNA lies in a region called the nucleoid, and they carry out respiration on their plasma membrane. Eukaryotic cells of plants, animals, fungi and protists have a nucleus with a nuclear membrane and organelles such as mitochondria, the Golgi apparatus, the endoplasmic reticulum and, in plants, chloroplasts. Mitochondria are called the powerhouse of the cell because they make ATP by aerobic respiration, and they carry their own DNA and 70S ribosomes, a sign of their bacterial origin.
A is wrong because most bacteria also have a cell wall, made of peptidoglycan.
B is wrong because every living cell, prokaryotic or eukaryotic, is bounded by a plasma membrane.
C is wrong because all cells contain the nucleic acids DNA and RNA.
Exam tip: prokaryote, no nucleus and no membrane-bound organelles, 70S ribosomes; eukaryote, nucleus, organelles, 80S ribosomes.
Practice Questions
View allWhich one of the following is the 'energy currency' for cellular processes?
- A.Glucose
- B.ATP
- C.ADP
- D.Pyruvic acid
Show answer
Adenosine triphosphate stores energy in its phosphate bonds and releases it wherever the cell needs it, so it is called the energy currency of the cell.
Read the full explanation →Which one of the following is the correct reactivity order of metals reacting with dilute HCl?
- A.Mg > Al > Zn > Fe
- B.Mg < Al < Zn < Fe
- C.Mg > Zn > Fe > Al
- D.Fe > Mg > Al > Zn
Show answer
This is the order in which these metals stand in the reactivity series, and it matches how vigorously they release hydrogen from dilute hydrochloric acid.
Read the full explanation →Deficiency of iron causes
- A.Anaemia
- B.Scurvy
- C.Rickets
- D.Cholera
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Iron is needed to make haemoglobin, so too little iron means too little haemoglobin and a reduced ability of the blood to carry oxygen.
Read the full explanation →Consider the following statements regarding waves : 1. If the particles of a medium move along the direction of motion of the wave, the wave is called a longitudinal wave. 2. If the particles of a medium move perpendicular to the direction of motion of the wave, the wave is called a transverse wave. 3. Transverse waves may involve change in the shape of the medium, whereas longitudinal waves involve change in the density of the medium. Which of the statements given above is/are correct ?
- A.1 and 2 only
- B.1 only
- C.2 and 3 only
- D.1, 2 and 3
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All three statements correctly describe how particles move in the two kinds of mechanical waves. In a longitudinal wave, such as sound in air, the particles vibrate back and forth along the direction in which the wave travels.
Read the full explanation →In paper manufacturing, degumming of the raw material is done using
- A.sulphuric acid
- B.bleaching powder
- C.caustic soda
- D.nitric acid
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In paper making the raw plant material is cooked with caustic soda, which dissolves the gums, resins and lignin that bind the cellulose fibres together.
Read the full explanation →