A
What is the actual time shown on the clock? (refer to slides)
8:25pm
List 3 examples of animal tissues.
Muscle, epithelial, nerve, connective
A mixture of acetone and ethanol is heated in a fractional distillation set-up. Acetone has a boiling point of 56°C while ethanol has a boiling point of 78°C. Which substance is distilled out last?
Ethanol
Name two organelles found in both plant and animal cells.
Vacuole, plasma membrane, cytoplasm, nucleus
Give an example of chromatography in our daily lives.
- Identify dyes in inks used in cheque forgery
- Identify drugs used by athletes in sport competitions
- Identify strands of DNA in blood samples
- Identify food colourings in food products
Label the parts of the cell shown (slides).
Vacuole, plasma membrane, mitochondria, etc
Correct the mistakes in this ray diagram
- dotted line should be used for measuring distance
- arrow head is facing the incorrect direction
- incident ray is incorrect
Explain how the structures of the root hair cell helps the cell do its job effectively.
The long and thin extension increase surface area to volume ratio of the cell to increase the rate of absorption of water and mineral salts into the cell.
A large central vacuole maintains high concentration of sugar and mineral salt in cell sap to absorb more water
Name an object we use in daily life that makes use of convex mirrors
Mirrors at blind spots on the road, surveillance mirrors in shops, car side-mirrors
What happens to the speed and the direction of light when it travels from air to water?
Water is more optically dense than air so the light ray will slow down and bend towards the normal.
The further the dye spot from the start line in a chromatogram, the less soluble the dye is. Is this true or false? Explain why.
False, the most soluble substance will travel the furthest distance from the start line.
How do we test if a solution is saturated?
Ans: Method 1: A solution is saturated when the added solute can no longer be dissolved in the solution.
OR
Method 2: Heat the solution to evaporate most of the solvent. Dip a glass rod into the heated solution and lift it. The solution is saturated when small crystals start to form on the cool glass rod when it is lifted.
Tricia stands 2m in front of a mirror. A pot of flowers is located 4.5m behind her. What is the distance from Tricia's eyes to the image of the pot of flowers?
8.5m (2+4.5+2)
List 1 use and 1 danger of infrared radiation
Uses: Thermal imaging, Remote Controls and motion sensors
Dangers: burns skin, damages eyes
Red blood cells do not have a nucleus. Explain how this adaptation helps them transport oxygen more efficiently.
The absence of the nucleus allows for packing of more haemoglobin in each cell, which binds to more oxygen, increasing the rate of diffusion of oxygen into the red blood cell.
“Division of labour” happens in multicellular organisms. Explain what this means and why it is important for survival.
•The specialisation of cells to perform specific functions is known as division of labour.
•Ensures smooth and efficient functioning of the multicellular organism and its survival by enabling different functions to be carried out at the same time
Bob shines a green light on a yellow ball. What colour does the ball appear?
Green
An observer looks at an object lying at the base of a swimming pool. He sees the image of the object. The real depth of the object is 3 metres. The apparent depth is 2.3 metres.
Calculate the refractive index of water.
refractive index = real depth/apparent depth = 1.30 (3sf)
What is the angle of reflection? (refer to slides)
70degrees
Diamond has a refractive index of 2.42 while water has a refractive index of 1.33. What happens when light travels from diamond to water?
- Light is going from optically dense medium to a less optically dense medium
- The speed of light speeds up when it enters water
- The light bends away from the normal
How would you separate copper(II) sulfate from a mixture of copper(II) sulfate, sand and water?
Ans: 1. Filter the mixture to remove the sand. The filtrate will contain copper(II) sulfate solution.
2. Use crystallisation to obtain copper(II) sulfate from the solution.
Determine the position of the mirror image (refer to slides)
D
How would you separate water from a mixture of salt, water and ethanol? (ethanol has a boiling point of 78°C)
Ans: 1. Fractional distillation to separate ethanol out
2. Use simple distillation to collect the water from the remaining salt solution
Why does the doctor stand in a different room when she conducts the X-Ray?
To avoid prolonged exposure to X-Rays, which causes mutation in cells when exposed for a long time
Smaller cells often have a larger surface area to volume ratio than bigger cells. Explain why this is important for the movement of substances into and out of cells.
This is important because it allows substances such as oxygen, nutrients, and waste materials to move in and out of the cell more quickly.
If a cell becomes too large, it may not get enough nutrients or remove waste fast enough to stay alive. Therefore, having a large surface area to volume ratio helps cells function efficiently.