Cell: The Unit of Life Chapter-Wise Test 10

Correct answer Carries: 4.

Wrong Answer Carries: -1.

A eukaryotic cell has extensive rough endoplasmic reticulum, a prominent Golgi apparatus and large, numerous nucleoli. Which conclusion is best supported by this combination?

The cell is primarily storing starch and oils in leucoplasts.
The cell is actively synthesising, processing and secreting proteins.
The cell is mainly carrying out intracellular digestion at acidic pH.
The cell has become specialised for active transport across the tonoplast.
2

RER is abundant in cells involved in protein synthesis and secretion. The Golgi apparatus modifies and packages proteins, while large and numerous nucleoli occur in cells actively carrying out protein synthesis because the nucleolus synthesises ribosomal RNA.

The tonoplast of a plant cell loses its ability to transport substances against their concentration gradients. Which change is most likely?

The vacuole will begin synthesising proteins on 80S ribosomes.
The vacuole will become continuous with the nuclear envelope.
The vacuole will acquire cristae to increase its membrane area.
The high concentration of certain ions inside the vacuole will be difficult to maintain.
4

The tonoplast transports several ions and other materials into the vacuole against concentration gradients. Loss of this function would prevent the vacuole from maintaining concentrations significantly higher than those in the cytoplasm.

An organelle is double-membrane-bound and contains circular DNA and 70S ribosomes. Its internal membranous sacs bear pigments, while its surrounding matrix contains enzymes for carbohydrate synthesis. Which organelle is it?

Chloroplast
Mitochondrion
Golgi apparatus
Lysosome
1

Both mitochondria and chloroplasts contain circular DNA and 70S ribosomes, so those features alone do not distinguish them. Pigment-bearing thylakoids and enzymes for carbohydrate synthesis in the stroma identify the organelle as a chloroplast.

A locomotory structure is covered by the plasma membrane and contains nine peripheral microtubule doublets surrounding two central microtubules. What can be inferred?

It is a bacterial flagellum composed of a filament, hook and basal body.
It is a centriole containing nine peripheral microtubule triplets.
It is a eukaryotic cilium or flagellum containing a 9+2 axoneme.
It is a bacterial pilus involved primarily in attachment.
3

A membrane-covered structure with a 9+2 axoneme is a eukaryotic cilium or flagellum. Bacterial flagella are structurally different, while centrioles possess nine peripheral triplets rather than a 9+2 arrangement.

A chemical selectively prevents the Golgi apparatus from packaging materials into vesicles. Which pair of cellular processes would be most directly affected?

ATP production and mitochondrial fission
Formation of lysosomes and delivery of secretory materials
Lipid synthesis and steroidal-hormone synthesis
Ribosomal RNA synthesis and movement through nuclear pores
2

The Golgi apparatus packages materials for intracellular delivery or secretion. Lysosomes are also formed through Golgi packaging. ATP production occurs in mitochondria, while lipid and steroid synthesis occurs mainly in the SER.

Consider the following changes during the maturation of a plant cell:

I. The capacity of the primary wall for growth diminishes.
II. A secondary wall forms towards the plasma membrane.
III. Cytoplasmic connections with neighbouring cells may still pass through the walls.

Which option correctly evaluates these statements?

Only statement I is correct.
Only statements I and II are correct.
Only statements II and III are correct.
Statements I, II and III are correct.
4

The primary wall grows in a young cell, but this capacity diminishes with maturity. The secondary wall is deposited on the inner side, towards the plasma membrane. Plasmodesmata may traverse the walls and connect neighbouring cytoplasms.

A change makes the lipid bilayer of a cell membrane much less fluid. Which group of processes is most likely to be affected because membrane fluidity is important for all of them?

Cell growth, intercellular-junction formation, secretion, endocytosis and cell division
Chromatin condensation, satellite formation and ribosomal RNA synthesis
Formation of grana, mitochondrial fission and synthesis of starch
Construction of bacterial pili, fimbriae and inclusion bodies
1

Membrane fluidity results from lateral movement of proteins within the quasi-fluid lipid bilayer. This property is important in cell growth, formation of intercellular junctions, secretion, endocytosis and cell division.

Two chromosomes are examined. Chromosome X has two equal arms, while chromosome Y has its centromere at the terminal end. How should X and Y be classified, respectively?

Submetacentric and acrocentric
Acrocentric and submetacentric
Metacentric and telocentric
Telocentric and metacentric
3

A metacentric chromosome has a centrally positioned centromere and two equal arms. A telocentric chromosome has a terminal centromere. Classification therefore requires relating arm lengths to centromere position.

A cell contains naked circular genomic DNA, 70S ribosomes, inclusion bodies and pigment-containing membranous extensions, but no membrane-bound organelles. Which interpretation is most appropriate?

It is a plant cell containing chloroplasts and a large central vacuole.
It is a photosynthetic prokaryotic cell possessing chromatophores.
It is an animal cell with an extensive endomembrane system.
It is a fungal cell containing mitochondria but lacking ribosomes.
2

Naked circular genomic DNA, 70S ribosomes, inclusion bodies and absence of membrane-bound organelles identify a prokaryotic cell. Pigment-containing membranous extensions are chromatophores found in some prokaryotes such as cyanobacteria.

Four structures are described below:

P: a single-membrane vesicle containing hydrolytic enzymes
Q: a membrane-bound space containing sap and excretory products
R: a double-membrane organelle with cristae
S: a double-membrane organelle with thylakoids

Which identification is correct?

P—vacuole, Q—lysosome, R—chloroplast, S—mitochondrion
P—microbody, Q—Golgi apparatus, R—nucleus, S—chloroplast
P—lysosome, Q—microbody, R—mitochondrion, S—Golgi apparatus
P—lysosome, Q—vacuole, R—mitochondrion, S—chloroplast
4

Lysosomes contain hydrolytic enzymes, while vacuoles contain water, sap, excretory products and other materials. Mitochondria possess inner-membrane cristae, whereas chloroplasts contain thylakoids arranged into grana.

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