KEY CONCEPTS IN BIOLOGY

Question 1

What is the difference between an electron microscope and a light microscope?

Answer 1

A light microscope is designed for more regular use. It has a lower magnification and resolution but can be used for living cells. They use beams of light.
An electron microscope has a higher magnification and resolution but cannot be used on living cells. They use a beam of electrons. Electron microscopes are better at viewing sub cellular structures.

Question 2

What is the method used when preparing a microscope slide to view an onion sample?

Answer 2

1. Place a single drop of water onto a slide
2. Peel some onion skin and apply it to the drop of water. Ensure it is flat with no air bubbles.
3. Stain cells with iodine
   4.Place a coverslip over it.
4. Place a drop of stain next to the coverslip and draw it under the slip with filter paper.

Question 3

List the animal cell subcellular structures

Answer 3

Cytoplasm
Nucleus
Ribosome
Mitochondrion
Cell membrane

Question 4

List the plant cell subcellular structures

Answer 4

All animal cell structures, as well as
Cell wall
Permanent vacuole
Chloroplasts.

Question 5

List the bacterial cell subcellular structures

Answer 5

Cell membrane
Cell wall
Plasmid DNA
Chromosomal DNA
Flagellum (sometimes)

Question 6

Animal specialised cellls:

Answer 6

Gametes (Sperm and Egg)
Ciliated Epithelial cell

Question 7

Plant specialised cells:

Answer 7

Root hair cell
Palisade cell
Xylem and Phloem cells

Question 8

What is resolution in terms of Microscopy?

Answer 8

The ability of a Microscope to distinguish details of a specimen or sample.

Question 9

Why can’t a light microscope see certain subcellular structures?

Answer 9

Due to limits of resolution and size.

Question 10

How do you find total magnification?

Answer 10

Take the magnification of the current objective lens and multiply it by the eyepiece.
E.g. 10x40 = 400micrometers

Question 11

How do you find magnification using a real object?

Answer 11

Magnification = Size of image / size of real object

Question 12

What is the difference between Animal and Plant cells?

Answer 12

Animal Cells lack a cell wall, permanent vacuole and chloroplasts.

Question 13

What is visible on an animal cell through a LIGHT MICROSCOPE?

Answer 13

Membrane, Cytoplasm, Nucleus

Question 14

What is visible on a plant cell through a LIGHT MICROSCOPE?

Answer 14

Cytoplasm, Nucleus, Vacuole, Membrane, Wall, Chloroplast

Question 15

What is the function of the Ribosomes in a cell?

Answer 15

The Ribosomes are the centre of a process called ‘protein-synthesis’ where proteins are created for a cell.

Question 16

What is the function of the Mitochondria?

Answer 16

The mitochondria are where aerobic respiration takes place in a eukaryotic cell, releasing energy inside the mitochondria.

Question 17

What is the function of the nucleus?

Answer 17

The nucleus houses all genetic information and serves as a control centre for cells.

Question 18

What is the function of the cell membrane?

Answer 18

The cell membrane regulates the transportation of materials entering and exiting the cell.

Question 19

What is the function of the cell wall?

Answer 19

Strengthens the cell and supports the plant.

Question 20

What is the function of Chloroplasts?

Answer 20

Absorbs light energy for photosynthesis, as well as containing enzymes used for photosynthesis.

Question 21

How is a sperm cell adapted to its function?

Answer 21

The head contains genetic material for fertilisation inside a HAPLOID nucleus.
The acrosome in the head contains enzymes that allow the sperm to penetrate the egg.
The middle piece has many mitochondria for energy.
The cell also has a flagellum to propel itself.

Question 22

How is an egg cell adapted to its function?

Answer 22

Cytoplasm contains nutrients for the growth of the early embryo.
HAPLOID nucleus contains genetic material for fertilisation.
Cell membrane changes after 1 sperm enters so no more can enter.

Question 23

What are enzymes?

Answer 23

Proteins that function as biological catalstys.