ENDOPLASMIC RETICULUM (ER)& CELL ORGANELLES

MCQs

• Which of the following is a key difference between prokaryotic and eukaryotic cells?
  a) Prokaryotic cells have a nucleus.
  b) Eukaryotic cells have membrane-bound organelles.
  c) Prokaryotic cells are generally larger.
  d) Eukaryotic cells lack a plasma membrane.
• The nuclear region in prokaryotic cells is:
  a) Well defined and surrounded by a nuclear membrane.
  b) Called the nucleoid and not enclosed by a membrane.
  c) The site of ribosome production.
  d) Absent in all prokaryotes.
• Prokaryotic cells generally have:
  a) More than one chromosome.
  b) A single circular chromosome.
  c) Membrane-bound organelles.
  d) A complex system of endoplasmic reticulum.
• Which of the following is NOT a characteristic of eukaryotic cells?
  a) Larger size (5-100 µm) compared to prokaryotes.
  b) Presence of membrane-bound organelles.
  c) A single circular chromosome.
  d) Well-defined nucleus surrounded by a nuclear membrane.
  Cell Organelles
• The endoplasmic reticulum (ER) is primarily involved in:
  a) Energy production through cellular respiration.
  b) Protein synthesis and lipid metabolism.
  c) Waste removal and cellular detoxification.
  d) Cellular movement and structural support.
• The rough endoplasmic reticulum (RER) appears rough due to the presence of:
  a) Lipids
  b) Carbohydrates
  c) Ribosomes
  d) DNA
• Which organelle is responsible for the synthesis of lipids and steroids?
  a) Rough endoplasmic reticulum (RER)
  b) Smooth endoplasmic reticulum (SER)
  c) Golgi apparatus
  d) Lysosomes
• Membrane biogenesis involves the:
  a) Breakdown of old cell membranes.
  b) Synthesis of new cell membranes using proteins and lipids.
  c) Transport of materials within the cytoplasm.
  d) Production of energy for cellular processes.
• Which of the following is NOT a function of the endoplasmic reticulum?
  a) Transport of materials within the cell.
  b) Protein synthesis (RER).
  c) Lipid synthesis (SER).
  d) Energy production.
• Which of the following is an example of a cell organelle?
  a) Plasma membrane
  b) Cell wall (in plants)
  c) Endoplasmic reticulum
  d) Cytoplasm
  Answer Key:
• b)
• b)
• b)
• c)
• b)
• c)
• b)
• b)
• d)
• c)

ASSERTION REASON

Absolutely! Let’s break down the provided text into Assertion-Reason questions with explanations.
Assertion-Reason Questions and Answers

1. Assertion: Eukaryotic cells are generally larger than prokaryotic cells.
   Reason: Eukaryotic cells have a nucleus and membrane-bound organelles, which increase their complexity and size.
   Answer: Both Assertion and Reason are true, and Reason is the correct explanation for the Assertion.
   Explanation: The text explicitly states the size difference and links it to the presence of organelles in eukaryotic cells.
2. Assertion: The nuclear region in prokaryotic cells is poorly defined.
   Reason: Prokaryotic cells lack a nuclear membrane.
   Answer: Both Assertion and Reason are true, and Reason is the correct explanation for the Assertion.
   Explanation: The text contrasts “well defined” nuclei in eukaryotes with the lack of a nuclear membrane (and thus a defined nucleus) in prokaryotes. The term “nucleoid” isn’t used in the provided text, but the absence of a membrane is the key point.
3. Assertion: Ribosomes are present in both prokaryotic and eukaryotic cells.
   Reason: Ribosomes are essential for protein synthesis, a process common to all living cells.
   Answer: Both Assertion and Reason are true, and Reason is the correct explanation for the Assertion.
   Explanation: The text mentions ribosomes in “all active cells” and links them to protein manufacture, implying their universal presence and function.
4. Assertion: The endoplasmic reticulum (ER) is a network of membrane-bound tubes and sheets found in eukaryotic cells.
   Reason: The ER is involved in protein and lipid synthesis, as well as detoxification, all of which require extensive membrane surfaces.
   Answer: Both Assertion and Reason are true, and Reason is the correct explanation for the Assertion.
   Explanation: The text describes the ER’s structure and links it to the synthesis of proteins and lipids. While detoxification isn’t explicitly mentioned in this excerpt, it is a known function of the ER, particularly the smooth ER in liver cells.
5. Assertion: The smooth endoplasmic reticulum (SER) appears rough under a microscope.
   Reason: The SER is studded with ribosomes, which give it a rough appearance.
   Answer: The Assertion is false, but the Reason is true.
   Explanation: The text explicitly states that the rough ER (RER) appears rough due to ribosomes, while the smooth ER (SER) lacks ribosomes and has a smooth appearance.
6. Assertion: Membrane biogenesis involves the synthesis of new cell membranes.
   Reason: Proteins and lipids synthesized in the ER are transported to the plasma membrane, contributing to its growth and repair.
   Answer: Both Assertion and Reason are true, and Reason is the correct explanation for the Assertion.
   Explanation: The text defines membrane biogenesis and links it to the ER’s role in synthesizing membrane components (proteins and lipids).
7. Assertion: The Golgi apparatus is involved in modifying and packaging proteins.
   Reason: Proteins synthesized in the ER are transported to the Golgi apparatus for further processing and sorting.
   Answer: While the assertion and reason are related, the text doesn’t explicitly explain the Golgi’s function in this excerpt. Therefore, based solely on THIS text:
   Answer: Neither the Assertion nor the Reason is explicitly explained in this text.
   Explanation: Although the text mentions the Golgi apparatus as an important organelle, it doesn’t provide details about its specific functions. This would require additional biological knowledge beyond the provided excerpt

Two marker questions

Okay, here are two 2-marker questions based on the provided text, along with their answers:
Question 1:
(a) State two differences between prokaryotic and eukaryotic cells based on the information given in the text.
(b) What is the function of ribosomes in a cell?
Answer:
(a)

• Prokaryotic cells are generally smaller (1-10 µm) than eukaryotic cells (5-100 µm).
• Prokaryotic cells lack membrane-bound organelles, including a nucleus, while eukaryotic cells have membrane-bound organelles, such as a nucleus. (Or: Prokaryotic cells have a poorly defined nuclear region, while eukaryotic cells have a well-defined nucleus surrounded by a nuclear membrane.)
• Prokaryotic cells have a single chromosome, while eukaryotic cells have more than one chromosome.
  (b) Ribosomes are the sites of protein manufacture in a cell.
  Question 2:
  (a) Describe the structure of the endoplasmic reticulum (ER) as mentioned in the text.
  (b) What is membrane biogenesis and how is the ER involved in this process?
  Answer:
  (a) The endoplasmic reticulum (ER) is a large network of membrane-bound tubes and sheets. It looks like long tubules or round or oblong bags (vesicles). The ER membrane is similar in structure to the plasma membrane. There are two types: rough ER (RER) and smooth ER (SER).
  (b) Membrane biogenesis is the process of synthesizing new cell membranes. The ER is involved because it manufactures proteins and lipids, which are essential components of cell membranes. These proteins and lipids are then transported to the plasma membrane, contributing to its growth and repair