Week 1: CS Quiz

The diagram shows plant cells.

Which structure would also be found in animal cells?

• A

• B

• C

• D

Answer explanation

There are only 3 structures you need to remember in ANIMAL CELL:

1. Nucleus.

2. Cell Membrane.

3. Cytoplasm.

*All these structures also exist in PLANT CELLS!

A mixed culture of living and non-living cells is placed in a red stain.

Only non-living cells take up the stain.

Which structure prevents the stain entering the living cells?

• Cell Wall

• Cell Membrane

• Cytoplasm

• Vacuole

Answer explanation

Cell surface membrane only allows certain molecules to enter and leave the cell.

So, this living structure prevents the entering of the red stain.

*Cell wall is non-living, therefore it allows the liquid to pass through.

Which structure in the plant cell contains chromosomes?

• A

• B

• C

• D

Answer explanation

The nucleus contains chromosome.

This chromosome carries DNA.

DNA is the genetic materials. It carries different "coding" for every single person that makes you unique from other.

The diagram shows a plant cell as seen under a microscope.

What are the functions in the cell of the numbered parts?

• Controlling entry of substance = 1

  Synthesis of Carbohydrates = 3

• Controlling entry of substance = 3

  Synthesis of Carbohydrates = 1

• Controlling entry of substance = 3

  Synthesis of Carbohydrates = 2

• Controlling entry of substance = 2

  Synthesis of Carbohydrates = 1

Answer explanation

1 = Chloroplast.

It contains the green pigment called Chlorophyll.

Chlorophyll used to trap sunlight in the process of photosynthesis.

During Photosynthesis, Carbohydrate + Oxygen is made.

2 = Cell Surface Membrane.

It selectively controls the passage of substance entering and leaving the cell.

3 = Cellulose cell wall.

It provides shape, support, and protection to the cell.

The diagrams show some pieces of potato in four sugar solutions with different concentrations of water.

In which solution will the potato piece take up water from the solution and swell?

• A

• B

• C

• D

Answer explanation

Osmosis =

The movement of water molecules from high water potential to low water potential through a partially permeable membrane. Down the water potential gradient.

A student adds different loads to  the end of a spring. She measures the extension in each case and plots a graph of extension against load.

Which graph is correct?

• A

• B

• C

• D

Answer explanation

According to Hooke's Law, the stress (load) applied on a body is directly proportional to strain (extension) produced.

The motion of an object is represented by a speed-time graph. 

Which statement about the object is correct?

• It is at rest

• It is moving with increasing speed

• It is moving at uniform speed

• It is moving with uniform non-zero acceleration

Answer explanation

The object is travelling in equal distances in equal intervals of time.

*This is a SPEED-TIME GRAPH!

Alan and Sarah are sitting on a seesaw. Alan is 1.5m from the pivot and the seesaw is in equilibrium.

Alan has a weight of 800N and Sarah has a weight of 600N. 

What is distance X? 

• 1.1 m

• 2.0 m

• 0.5 m

• 0.75 m

Answer explanation

The Principle of Moments states that when a body is balanced, the total clockwise moment about a point equals the total anticlockwise moment about the same point.

Equation.

Moment = force F x perpendicular distance from the pivot d.

Moment on Alan = Moment on Sarah

              800 x 1.5 = 600 x X

                            X = 2.0m

Which part of the speed-time graph shows constant non-zero acceleration?

• A

• B

• C

• D

Answer explanation

Speed and directions are changing , which means there is rate of change of velocity.  Therefore.  there is non-zero acceleration.

Acceleration = change of velocity / time

*When there is change in velocity = there is Acceleration!

A = Positive non-constant Acceleration (Curve graph).

B = Zero acceleration (Because the speed is constant).

C = Negative non-constant deceleration (Curve graph) (the speed is slow down).

D = Constant deceleration

The diagram show four possible arrangement of different forces applied to open the same door.

• A

• B

• C

• D

Answer explanation

Turning effect is greatest when the force applied is furthest away from pivot.