CB1: Key Concepts in Biology

Question 1

Define Magnification

Answer 1

The ability to enlarge smaller object’s appearance

Question 2

What is the formula to calculate magnification using the two lenses?

Answer 2

eyepiece lens x objective lens

Question 3

How do you calculate magnification based off of image size?

Answer 3

magnification = image size/ actual size

Question 4

Define resolution

Answer 4

How detailed an image is

Question 5

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

Answer 5

A light microscope uses light to display enlarged images and has a lower resolution as compared to an electron microscope. An electron microscope uses electrons to display images and has a higher resolving power than the light microscope

Question 6

What is the limitation of an electron microscope?

Answer 6

You can’t observe living things because samples are placed in vacuums

Question 7

What is the difference between a prokaryotic and eukaryotic cell?

Answer 7

Eukaryotic cells: cells with a nucleus eg: animal and plant cells
Prokaryotic cells: cells without a nucleus eg: bacteria

Question 8

What is the role of the nucleus?

Answer 8

• controls the cell and its activities
• contains chromosomes

Question 9

What is the role of the cell membrane?

Answer 9

• thin bag
• controls what enters and leaves

Question 10

What is the role of the mitochondria?

Answer 10

Where aerobic respiration occurs

Question 11

What is the role of the ribosomes?

Answer 11

Makes proteins for the cells

Question 12

What is the role of the chloroplasts?

Answer 12

• contain chlorophyll
• traps energy from the sun to be used in photosynthesis

Question 13

What is the role of the cell wall?

Answer 13

• made of cellulose
• supports and protects the cell

Question 14

What is the role of the vacuole?

Answer 14

• stores cell sap
• helps keep the cell rigid and firm

Question 15

Define specialised cells

Answer 15

Cells with specific functions/ jobs

Question 16

What are the adaptations of an egg cell?

Answer 16

• haploid for fertilisation to make a diploid cell
• jelly coat protects the egg and hardens after fertilisation to prevent other sperm cells from entering
• cell membrane: fuses with the sperm cell membrane. also hardens after fertilisation to prevent other sperm cells from entering
• cytoplasm: packed with nutrients to supply fertilised egg cell with energy and raw materials for growth and development of embryo

Question 17

What are the adaptations of a sperm cell?

Answer 17

• haploid
• streamlined shape: helps it to swim faster
• lots of mitochondria: releases lots of energy
• tail to move
• acrosome: contains enzymes that break down substances in the jelly coat of the egg

Question 18

What are the adaptations of ciliated epithelial cells?

Answer 18

• cilia covered in cell membrane
• contains strands of a substance that can contract and cause wavy movement

Question 19

What is the role of the chromosomal DNA?

Answer 19

• controls cells activities
• found free in the cytoplasm

Question 20

What is the role of the plasmids?

Answer 20

• controls some of the cell’s activities
• extra DNA

Question 21

What is the role of the flagellum?

Answer 21

• long thin ‘whip-like’ tails
• so bacteria can move

Question 22

Define enzymes

Answer 22

Biological catalysts

Question 23

What is the role of an enzyme?

Answer 23

It can break down large substances into small ones (breakdown) and join small substances into larger ones (synthesis)

Question 24

What does protein break down into?

Answer 24

Amino acids

Question 25

What does starch break down into?

Answer 25

Glucose

Question 26

What do lipids break down into?

Answer 26

Fatty acids and glycerol

Question 27

What is the active site of an enzyme?

Answer 27

The part of the enzyme where the substrate fits into

Question 28

Explain the lock and key hypothesis

Answer 28

The shape of the active site matches the shape of its substrate, which forms an enzyme-substrate complex. Once bound, the reaction takes place on the enzymes surface.

Question 29

What happens when an enzyme becomes 'denatured'?

Answer 29

The shape of the active site changes, so the substrate no longer fits in it

Question 30

What three conditions affect enzyme activity?

Answer 30

- temperature - pH - substrate concentration

Question 31

What occurs to an enzyme when we pass its optimum temperature/ pH?

Answer 31

It becomes denatured

Question 32

What occurs to an enzyme when we pass its optimum substrate concentration?

Answer 32

All the enzymes become saturated, so increasing the substrate concentration after this point will have no affect on the enzymes themselves.

Question 33

How do we calculate rate?

Answer 33

change in measured substance / time it takes for change to be displayed

Question 34

Define diffusion

Answer 34

When particles move from an higher concentration to a lower concentration. It doesn't require energy

Question 35

Define osmosis

Answer 35

The diffusion of solvents through a partially permeable membrane. It doesn't require energy

Question 36

Define active transport

Answer 36

When cells transport molecules against a concentration gradient/ transport those that can't fit through the partially permeable membrane. This requires energy

Question 37

How do you calculate the percentage change in mass?

Answer 37

((final mass - initial mass)/initial mass) x 100

Question 38

What enzyme causes the breakdown of carbohydrates?

Answer 38

Carbohydrases

Question 39

What enzyme causes the breakdown of proteins?

Answer 39

Protease

Question 40

What enzyme causes the breakdown of lipids?

Answer 40

Lipases

Question 41

What is a hypotonic solution?

Answer 41

More water than sugar

Question 42

What is an isotonic solution?

Answer 42

Equal amounts of water and sugar

Question 43

What is a hypertonic solution?

Answer 43

More sugar than water

Question 44

What is the difference between animal cells and plant cells in a hypotonic solution?

Answer 44

Animal cell: Lysed (cell membrane is broken or destroyed) Plant cell: Turgid (tissues swollen by water uptake) normal

Question 45

What is the difference between animal cells and plant cells in an isotonic solution?

Answer 45

Animal cell: normal Plant cell: flaccid (drooping/inelastic due to lack of water)

Question 46

What is the difference between animal cells and plant cells in a hypotonic solution?

Answer 46

Animal cell: shrivelled Plant cell: plasmolysed (shrinking of the cytoplasm from the wall of the living cell due to the lack of water)