B1 - Cell biology

Question 1

What is the job of the cell membrane?

Answer 1

To hold together the cell and control what goes in and out .

Question 2

What is the job of the cytoplasm?

Answer 2

Where chemical reactions take place, it contains enzymes

Question 3

What is the job of the Nucleus?

Answer 3

To hold the genetic material that controls the cells activities

Question 4

What is the job of Rhizomes?

Answer 4

They produce protein for amino acids

Question 5

What is the job of Mitochondria?

Answer 5

They produce energy and perform aerobic respiration

Question 6

What three structures do only plant cells have?

Answer 6

1) Vacuole
2) Cell Wall
3) Chloroplasts

Question 7

The head of a pin in 1 mm in diameter.

How many prokaryotic cell would fit length ways?

Answer 7

1μm = 0.001 mm
0.001mm * 1000 = 1 mm

so 1000 cell would ft across

Question 8

Magnification = Size of image / size of real object

What is the size of an image in cm where the magnification is x2000 and the size of the cell is 0.012 mm ?

Answer 8

2000*0.012
= 24 mm / 10

=2.4 cm

Question 9

How does magnification and resolution compare between electron and light microscopes?

Answer 9

Electron microscopes have a higher resolution and magnification than light microscopes, this means things can be seen with greater detail.

Question 10

What objective lens should you start with?

Answer 10

The lowest magnification

Question 11

How should a student go about producing a scientific drawing of a cell under a microscope.

Answer 11

1) Use a sharp pencil
2) Don’t shade or colour the diagram
3) Use clear unbroken lines
4) Label with horizontal lines
5) Label the diagram with the cell name and magnification
6) Draw what you see
7) Title the drawing

Question 12

Why are stains used when viewing thing under a microscope?

Answer 12

Some specimens are colourless.

Question 13

How are root hair cells specialised?

Answer 13

Long finger - like projection increases surface area for absorption of water

Question 14

How is a xylem specialised?

Answer 14

Cells are hollow in the centre and have no end cell walls. They form a continuous tube of transporting water from roots to leaves.

Question 15

How is a phloem specialised?

Answer 15

Very few sub-cellular structures and hols in the end cell walls allow dissolved sugars to move from one cell to the next.

Question 16

How is a sperm cell specialised to help it achieve it’s function?

Answer 16

It has a tail to enable it to swim. It has lots of mitochondria to give it lot’s of energy, and a head that contain enzymes to help it penetrate the egg.

Question 17

What is the chemical molecule that chloroplast are made of?

Answer 17

DNA

Question 18

What is mitosis?

Answer 18

The division of cells to make two identical daughter cells.

Question 19

What is binary fission?

Answer 19

The rapid division of bacteria cells.

Question 20

Suggest a limiting factor of binary fission

Answer 20

1) A lack of nutrients

2) A lack of oxygen

Question 21

Where are stem cells found in plants?

Answer 21

The meristem

Question 22

Describe the benefits of cloning plants from stem cells

Answer 22

1) Plants can be produced quickly and cheaply
2) Rare plants can be cloned to prevent extinction
3) Large numbers of identical crops with desirable features e.g.resistance to TMV virus

Question 23

Why can’t all body cells be used to grow different types of cells?

Answer 23

Because differentiated cells can’t change into another type of cell.

Question 24

Describe what therapeutic cloning is.

Answer 24

The production of an embryo with the same genes as the patient.

Question 25

Explain the benefit of using stem cell produced by therapeutic cloning for medical treatments.

Answer 25

The cells won’t be rejected by the donor because they have the same genes.

Question 26

What are the ethical issues surrounding the use of embryonic stem cells in medicine and research?

Answer 26

Some people feel that embryos are potential life so shouldn’t be used for experiments, there are also other ways to collect stem cells. However, others believe that curing those who already exist is more important, that and embryos are collected from places where they are unwanted anyway.

Question 27

Define diffusion in terms of gas particles

Answer 27

The spreading out of gas particles resulting in movement from a high concentration to a low concentration.

Question 28

What factors affect diffusion into a cell

Answer 28

1) concentration
2) surface area
3) temperature
4) Distance
5) permeability of the membrane

Question 29

Define osmosis

Answer 29

The movement of water molecules across a semi-permual membrane, from a region of high concentration from low.

Question 30

Define active transport

Answer 30

The movement of a substance against the concentration gradient (from a high concentration to a low concentration)

Question 31

Describe the function and structure of the root hair cells of a plant.

Answer 31

The function of the root hair cell is to take up substances from the soil. The cells have hairs that stick into the soil. The hairs increase surface are allowing for more osmosis and active transport.

Question 32

Emphysema is a disease that weakens and breaks down the wall of the alveoli.

Explain why the person may experience lower energy levels during physical exercise.

Answer 32

The surface area of the lungs is reduced, the amount of diffusion happening has decreased. This means there is less oxygen for respiration.

Question 33

Describe and explain how the structure of the small intestine is adapted for absorbing.

Answer 33

The intestine is covered in villi, which increases the surface area for absorption. There is a good blood supply which maintains a concentration gradient. The villi have a single layer of cells which give a short diffusion pathway.