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lecture 6

Total questions: 40

Worksheet time: 20mins

Name
Class
Date
1.

The main function of intermediate filaments is:

a)

Intracellular transport

b)

Mechanical strength

c)

Cell signaling

d)

ATP generation

2.

Intermediate filaments are described as:

a)

Rigid rods

b)

Strong and ropelike

c)

Hollow tubes

d)

Thin and flexible

3.

Which intermediate filaments form a supportive mesh under the nuclear envelope?

a)

Keratins

b)

Vimentins

c)

Lamins

d)

Neurofilaments

4.

Mutations in lamins can cause:

a)

Progeria

b)

Cystic fibrosis

c)

Tay-Sachs disease

d)

Alzheimer’s disease

5.

Intermediate filaments are grouped into how many main classes?

a)

Two

b)

Three

c)

Four

d)

Five

6.

The major microtubule-organizing center in animal cells is the:

a)

Golgi apparatus

b)

Centrosome

c)

ER

d)

Nucleus

7.

Microtubules are built from:

a)

Actin monomers

b)

Tubulin dimers

c)

Intermediate filament proteins

d)

Keratins

8.

The behavior of alternating growth and shrinkage in microtubules is called:

a)

Treadmilling

b)

Dynamic instability

c)

Sliding filament

d)

Depolymerization

9.

Dynamic instability is driven by:

a)

ATP hydrolysis

b)

GTP hydrolysis

c)

Phosphorylation

d)

Proton gradients

10.

Which motor protein moves cargo toward the plus end of microtubules?

a)

Dynein

b)

Kinesin

c)

Myosin-I

d)

Myosin-II

11.

Dyneins move cargo:

a)

Toward the plus end

b)

Toward the minus end

c)

Bidirectionally

d)

Only in actin filaments

12.

Which organelle is pulled inward along microtubules by dynein?

a)

ER

b)

Golgi apparatus

c)

Lysosomes

d)

Ribosomes

13.

The microtubule arrangement in cilia and flagella is:

a)

9 + 0

b)

9 + 2

c)

13 + 0

d)

9 + 3

14.

The bending movement of cilia is caused by:

a)

ATP hydrolysis by myosin

b)

Sliding of actin filaments

c)

Dynein movement along microtubules

d)

Polymerization of tubulin

15.

Microtubules in axons are responsible for:

a)

Generating contractile forces

b)

Guiding transport of vesicles and organelles

c)

Synthesizing neurotransmitters

d)

Degrading proteins

16.

Actin filaments are:

a)

Rigid rods

b)

Thin and flexible

c)

Hollow tubes

d)

Rope-like structures

17.

Actin and tubulin polymerize by:

a)

Identical mechanisms

b)

Similar mechanisms

c)

Completely different mechanisms

d)

No mechanisms

18.

Regulation of actin filament polymer length is controlled by:

a)

Treadmilling

b)

Dynamic instability

c)

Motor proteins

d)

Phosphorylation

19.

Thymosin and profilin regulate actin by:

a)

Binding actin monomers and blocking addition

b)

Severing filaments

c)

Crosslinking filaments

d)

Promoting myosin sliding

20.

Actin-rich cortex underlies:

a)

Mitochondria

b)

The plasma membrane

c)

The nucleus

d)

The ER

21.

Lamellipodia are formed by:

a)

Polymerizing actin pushing the membrane

b)

Microtubule sliding

c)

Intermediate filament bundling

d)

Myosin filament thickening

22.

Actin filaments interact with myosin to form:

a)

Centrosomes

b)

Contractile structures

c)

Intermediate filaments

d)

Dynein arms

23.

Extracellular signals affect actin filaments by:

a)

Modifying their arrangement

b)

Preventing polymerization

c)

Blocking actin gene expression

d)

Destroying actin

24.

Myosin-II filaments enable:

a)

Vesicle transport

b)

Sliding of actin filaments for contraction

c)

Tubulin depolymerization

d)

Nuclear import

25.

A skeletal muscle is packed with:

a)

Sarcomeres

b)

Myofibrils

c)

Intermediate filaments

d)

Centrosomes

26.

The functional contractile unit of skeletal muscle is the:

a)

Myofibril

b)

Sarcomere

c)

Filopodium

d)

Lamellipodium

27.

Muscle contraction is explained by:

a)

Treadmilling

b)

Sliding filament mechanism

c)

Dynamic instability

d)

Vesicular transport

28.

Which molecule “walks” along actin filaments during contraction?

a)

Dynein

b)

Myosin-II

c)

Kinesin

d)

Profilin

29.

The myosin head movement is powered by:

a)

ATP hydrolysis

b)

GTP hydrolysis

c)

Ca²⁺ binding directly

d)

Mechanical stress

30.

Contraction is triggered by Ca²⁺ released from:

a)

Golgi

b)

Sarcoplasmic reticulum

c)

Mitochondria

d)

Endosomes

31.

Which proteins regulate actin–myosin binding in muscle?

a)

Troponin and tropomyosin

b)

Profilin and thymosin

c)

Dynein and kinesin

d)

Keratins

32.

Smooth muscle differs from skeletal muscle because:

a)

It lacks actin

b)

It contracts more slowly and with different regulation

c)

It uses microtubules instead of actin

d)

It has no myosin

33.

The leading edge of a crawling cell is pushed by:

a)

Actin polymerization

b)

Dynein sliding

c)

Intermediate filaments

d)

Centrosomes

34.

What is treadmilling in actin filaments?

a)

Growth at plus end, shrinkage at minus end

b)

Growth and shrinkage at both ends

c)

No change in filament length

d)

Severing of filaments

35.

Which cytoskeletal element provides tracks for vesicle transport?

a)

Intermediate filaments

b)

Microtubules

c)

Actin filaments

d)

Lamins

36.

Which cytoskeletal element provides tensile strength?

a)

Actin filaments

b)

Microtubules

c)

Intermediate filaments

d)

Myosin

37.

Which is NOT a cytoskeletal filament type?

a)

Actin filaments

b)

Microtubules

c)

Intermediate filaments

d)

Collagen

38.

A drug that prevents tubulin polymerization would block:

a)

Actin treadmilling

b)

Microtubule formation

c)

Intermediate filament assembly

d)

Lamin polymerization

39.

A drug that prevents actin polymerization would inhibit:

a)

Muscle contraction

b)

Cell crawling

c)

Lamellipodia formation

d)

All of the above

40.

Cilia beating in the respiratory tract is powered by:

a)

Kinesin

b)

Dynein

c)

Myosin-II

d)

Actin polymerization