Supplying the Cell B2.1

Question 1

What is meant by ‘Cell Cycle’?

Answer 1

Where cells grow and divide, over and over again.

Question 2

What are the three stages of the cell cycle?

Answer 2

Interphase, Mitosis and Cytokinesis

Question 3

What is the interphase?

Answer 3

The cell gets ready to divide. The cell grows, DNA duplicates and more organelles are made.

Question 4

What is Mitosis?

Answer 4

The genetic material separates to different ends of the cell, and the cell gets ready to divide into two daughter cells.

(See and study diagram).

Question 5

What are the four main stages of Mitosis

Answer 5

During mitosis the following events occur:
Chromosomes replicate, resulting in X-shaped chromosomes with two ‘arms’ known as chromatids
The chromosomes line up along the equator of the cell
The chromatids are separated and pulled to opposite ends of the cell
A new nucleus forms around each new group of chromosomes

Question 6

Mitosis occurs in all eukaryotic cells, why?

Answer 6

Replacing skin cells
Growth of an organism
Asexual reproduction (Plants)

Question 7

What is cell differentiation

Answer 7

Where a cell becomes specialised for a specific purpose.

Question 8

How are palisade leaf cells specialised for their purpose?

Answer 8

Tall shape - have a large surface area.
Thin so there are more of them, closer to the light.

Question 9

What are the specialised adaptations of a sperm cell?

Answer 9

Long tails and streamline head - easy to swim.
Lots of mitochondria to give the cell energy.

Question 10

What are stem cells and where are they found.

Answer 10

Undifferentiated cells (have the ability to turn into any cell), mainly found in embryos
But,
can be found in adult bone marrow (but cant go into any cell)

Question 11

In plants, where are the stem cells found?

Answer 11

Meristems.

Question 12

What is diffusion?

Answer 12

Movement of particles from an area of high concentration to a lower concentration.

Question 13

What is active transport?

Answer 13

Active transport is the movement of cells/ions across a cell membrane from a region of lower concentration to a region of higher concentration

Only one that requires energy

Question 14

What is osmosis?

Answer 14

Osmosis is the net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water.

A special case of diffusion for water.
Partially permeable membrane = membrane with very small holes in

Question 15

What is water potential?

Answer 15

The potential of water molecules to diffuse into or out of a solution.

Question 16

How does osmosis work when watering a plant and why do the leaves stay in place?

Answer 16

When watering a plant, you increase the water potential around the soil.
The water is drawn in through osmosis. This happens until the cells become turgid. (Plump and swollen). This helps keep the plant upright and in shape.

If you didn’t water a plant, the cells would become flaccid and droop.

Question 17

What are the three main factors that affect active transport, diffusion and osmosis?

Answer 17

Surface area- more space, more movement

Temperature - warmer then particles more faster, move quicker between concentration gradients

Concentration gradient - bigger difference in concentrations

Question 18

Describe the particle for investigating the effects of Osmosis

Answer 18

Cut ups cylinders of potato (or other starchy veg) - and weigh
Add into test tubes of different sugar solution concentrations
24hours later- Re weigh and calculate percentage change.

Percentage change = final - initial mass / initial mass x100

When plotted on a graph, where it hits the x axis, is typically the concentration of the vegetable normally.

Question 19

What is a cells with (a. 23 pairs) of chromosomes and (b. 23) chromosomes called.

Answer 19

A. Diploid
B. Haploid

Question 20

What are the advantages of cloning (from stem cells)?

Answer 20

Helps endangered species and crops.