B2: Cells

Question 1

What are common features of the cell that both animal and plant cells have?

Answer 1

A cell membrane, cytoplasm and a nucleus.

Question 2

What is the cytoplasm?

Answer 2

A jelly-like substance containing the other structures inside the cell

Question 3

What does the cytoplasm do?

Answer 3

The site of most chemical reactions in the cell

Question 4

What is the nucleus?

Answer 4

• An approximately spherical structure that occupies about 10% of the cell’s volume
• Located towards the centre of animal cells and towards the edge of plant cells

Question 5

What does the nucleus do?

Answer 5

• Contains the cell’s DNA
  (genetic code)
• Controls the activities of the cell
• Controls cell division

Question 6

What are ribosomes?

Answer 6

Ribosomes are the site of protein synthesis in the cell. Ribosomes are found either scattered freely in the cytoplasm or at times attached to a network of tube like membranes seen in the cytoplasm.

Question 7

What happens in the mitochondria?

Answer 7

Aerobic respiration happens in the mitochondria. In this process, useful energy is released when glucose is broken down in the presence of oxygen (producing carbon dioxide and water). The energy released is used to drive many chemical reactions inside the cell.

Question 8

What are chloroplasts and what do they do?

Answer 8

Chloroplasts are present in photosynthetic organisms, such as plants and certain algae. These structures contain the photosynthetic pigment chlorophyll, which absorbs light energy and converts it into chemical energy, glucose.

Question 9

What is the cell membrane?

Answer 9

• the outer layer of animal cells, that holds together the
  cell contents
• made up of fats and proteins

Question 10

What does the cell membrane do?

Answer 10

• controls the movement of substances into and out of
  the cell
• partially permeable membrane that allows some molecules to pass through it, while others cannot

Question 11

What are vacuoles?

Answer 11

• fill most of the space inside a plant cell
• contain a watery fluid called cell sap
• animals cells may contain vacuoles which are small and non-permanent
• also contain some substances such as ions, lipids and proteins

Question 12

What do vacuoles do?

Answer 12

• help the cell to stay rigid
• some substances can be stored in them

Question 13

What is the cell wall?

Answer 13

• the outermost structure in all plant cells
• mostly made of tough but slightly elastic cellulose fibres
• fibres form a mesh around the outside of the cell membrane

Question 14

What does the cell wall do?

Answer 14

• provides shape and support to the cell
• prevents the cell from bursting when it absorbs water

Question 15

What are bacteria?

Answer 15

A very simplified, single-celled living organisms, lacking complex and organised structures. As they lack internal structures, such as mitochondria, the metabolic reactions occur within the cytoplasm. The DNA is not in a separate membrane-bound nucleus.

Question 16

What are the cell features of bacteria?

Answer 16

• cell wall, enclosing the cell
• cell membrane, surrounding the cytoplasm
• cytoplasm, substance filling the cell where metabolic reactions take place
• ribosomes, for protein synthesis
• circular DNA, containing the genetic material
• plasmids, small loops of DNA containing a few genes that can be transferred to other bacteria.

Question 17

In a plant, there are 2 types of specialized cells, what are they?

Answer 17

The root hair cell and the palisade mesophyll cell

Question 18

What does the root hair cell look like and what does it do?

Answer 18

• Looks like a finger-like extension to provide a large surface area to volume ratio for absorption to happen.
• absorbs water and dissolved mineral ions from the soil

Question 19

What does the palisade mesophyll cell look like and what does it do?

Answer 19

• contains many chloroplasts
• tall box shape to absorb a lot of light passing through
• photosynthesis in the leaves

Question 20

What is the ciliated epithelial cell and what does it do?

Answer 20

• Cilia are hair-like extensions of the cell. They are constantly moving and sweep mucus long.
• They move mucus in the trachea and the bronchi of the lungs. Ciliated cells also move the ovum and zygote down the fallopian tube

Question 21

What is the neuron and what does it do?

Answer 21

• The axon is long so it can conduct impulses to distant parts of the body.
• Conducts electrical impulses to different parts of the body

Question 22

What is the red blood cell and what does it do?

Answer 22

• contains haemoglobin, the red protein which transports oxygen
• no nucleus, increasing the volume inside for many haemoglobin molecules
• biconcave shape provides a large surface area to volume ratio for absorption to happen
• transport of oxygen around the body in the bloodstream

Question 23

What are sperm cells and what do they do?

Answer 23

• the cell has a long flagellum to allow the sperm to travel to an egg
• many mitochondria to provide the energy needed
• sexual reproduction (it is the male gamete)

Question 24

What does cell division (mitosis) do?

Answer 24

Create new cells

Question 25

How does cell division (mitosis) make new cells?

Answer 25

In which a parent cell divides into two or more daughter cells.

Question 26

What is the process where a parent cell divides into two or more daughter cells?

Answer 26

Cell cycle

Question 27

What are tissues?

Answer 27

A group of cells with similar structures, and which work together to carry out a shared function

Question 28

What are organs?

Answer 28

A group of tissues, which work together to carry out specific functions

Question 29

What are organ systems?

Answer 29

A group of organs with related functions, which work together to carry out body functions

Question 30

What is the formula for total magnification in microscopes?

Answer 30

total magnification = (eyepiece lens magnification) × (objective lens magnification)

Question 31

What is the formula for total magnification in images?

Answer 31

magnification = size of image/size of object

Question 32

What unit is used to measure sub-cellular structures under a microscope?

Answer 32

Micrometre (µm)

Question 33

What is 1µm in mm (standard form)?

Answer 33

1µm = 1 x 10^-6 (µm = mm divided by 1000) (mm = µm multiply by 1000)