Biology By Example

Tim Prichard

Description

Biology by Example is a revision guide aimed at the AQA GCSE science courses grades 9-1. It does have extra content, so it also covers the majority of the Edexcel and other UK exam boards as well. Biology by Example like the other guides in this series, (Physics by Example and Chemistry by Example) are different to other revision guides on the market because they are centred around practice questions with fully worked and solved solutions. This means the student/teacher can follow the method step by step of how to approach and solve exam style questions in the three sciences. Including hints, tips and common mistakes students make to help describe the approach because it is necessary to fully understand successfully answer exam style questions in GCSE science. The guides all contain self-testing sections with answers and space for working.Biology by Example contains a huge array of different styles of questions from long answer, comprehension, multiple choice, matching sentence starters and endings, graph analysis and straightforward recall to name but a few. The three guides together have around 800 practice questions with solutions fully worked and written in an easy-to-follow way. This gives the student or teacher probably the most comphrensive source of revision material or lesson planning material for school science there is currently on the market.

Sujets

• Informatique

Informations

• Publié par: Distributed by eBookpartnership
• Date de parution: 19 avril 2022
• Nombre de lectures: 0
• EAN13: 9781839524943
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

First published 2022
Copyright © Tim Prichard 2022
The right of Tim Prichard to be identified as the author of this work has been asserted in accordance with the Copyright, Designs & Patents Act 1988.
All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, electrostatic, magnetic tape, mechanical, photocopying, recording or otherwise, without the written permission of the copyright holder.
Published under licence by Brown Dog Books and
The Self-Publishing Partnership Ltd, 10b Greenway Farm, Bath Rd, Wick, nr. Bath BS30 5RL
www.selfpublishingpartnership.co.uk

ISBN printed book: 978-1-83952-493-6
ISBN e-book: 978-1-83952-494-3
Cover design by Andrew Prescott Internal design by Jenny Watson Design Illustrations by Jasmine Cottage Marketing
Printed and bound in the UK This book is printed on FSC certified paper
CONTENTS
MICROSCOPY
PLANT AND ANIMAL CELLS
Cell differentiation or specialisation
Diffusion – cell transport
Osmosis
Osmosis in animal cells
Osmosis in plant cells
Active transport
Surface area to volume ratio
Cell division and sexual/asexual reproduction
Short self-assessment on cells
LEVELS OF ORGANISATION AND ORGAN SYSTEMS
Food tests
Enzymes and food tests short self-assessment
Transport in the human body
The heart and blood
Gas exchange and the lungs
Heart and lungs short self-assessment test
Transport in plants
COMMUNICABLE AND NON-COMMUNICABLE DISEASES
THE HUMAN BODY’S NATURAL DEFENCES AGAINST DISEASE
Non-communicable diseases
Self-assessment on pathogens and disease
PHOTOSYNTHESIS
AEROBIC RESPIRATION
Short self-assessment on photosynthesis and respiration
HOMEOSTASIS
The role of hormones
Controlling sugar levels in the blood
Puberty and the menstrual cycle
Plant hormones and their responses to the environment
Self-assessment on responding to the environment
GENETICS, REPRODUCTION AND EVOLUTION
Self-assessment on reproduction, DNA, inherited conditions
Evolution and variation
The theory of evolution
Self-assessment on evolution and genetic engineering
CLASSIFICATION
ECOLOGY
Forest food web
Short self-assessment on ecosystems and interdependence
Cycles in nature
BIODIVERSITY AND MANAGING WASTE
Self-assessment on cycles
BIOMASS AND TROPHIC LEVELS
Self-assessment on biomass and trophic levels
MICROSCOPY
Microscopy as the name suggests involves using microscopes to study objects which are too small to be seen by the naked eye.
The first microscope was built by two Dutch spectacle-makers in the 1590s but later in the 1670s a Dutch lens maker called Antonie Van Leeuwenhoek designed and built a single lens microscope to study unicellular organisms such as bacteria and red blood cells. He is now recognised as the father of modern-day Microbiology.
Question 1
Label the diagram of a typical microscope which you might find in a school laboratory.

Question 2
What do we mean by Resolution or Resolving power?
Answer:
If two objects which are exceedingly small and close together, a microscope with a high resolution or resolving power can separate or distinguish between both points giving a clear image. If the microscope does not have a high resolution or resolving power, they will blur and appear to merge together.
Question 3
You will need to understand units when answering microscopy questions, so test yourself by filling in the gaps in the table below.
1,000 metres (m)
__________ kilometres (km)
1 metre (m)
__________ centimetres (cm)
1 centimetre (cm)
__________ millimetres (mm)
__________ millimetres (mm)
1,000 micrometres (µm)
1 micrometre (µm)
__________ nanometres (nm)
1 nm
1 × 10 -9 __________
Answers:
1,000 metres (m)
1 kilometre (km)
1 metre (m)
100 cm
1 centimetre (cm)
10 mm
1 millimetre (mm)
1,000 micrometres (µm)
1 micrometre (µm)
1,000 nanometres (nm)
1 nm
1 × 10 -9 m
Note:   or 1 billionth of a metre!
Question 4
Using the formula triangle below, make each term the subject of the equation.

Answers:

Question 5
An image of a cell in a microscope has a diameter of 2,000 µm. The actual cell has a diameter of 100 µm. What is the magnification of this microscope?
Answer:
Use the equation,

Question 6

The scale bar in the diagram measures 30 mm. This distance represents 3 µm. What is the magnification in this diagram?
Answer
• First change the mm into µm by multiplying by 1,000
• 30mm × 1,000 = 30,000
•
• 30,000/3 = 10,000
• Magnification = × 10,000
Question 7
A eukaryotic cell measures 5 µm in length. If the magnification is ×500, how big is the image?
Answer
Image = magnification × real size
Now convert real size into mm by dividing by 1,000

Question 8
A plant cell in a picture measures 12 mm across. If the actual size of the cell is 0.010 mm, what is the magnification?
Answer

(Both units in mm so do simple division)

Magnification is ×1,200
Question 9
A bacterial cell in a diagram measures 6 cm across. If the actual length of the bacteria cell is 4 µm, calculate the magnification of the diagram.
Answer

Note: in this question we need to change the terms into the same units, so I chose to put them both into micrometres (µm)
Question 10
a) The nucleus of an animal cell on a computer screen measures 2.5 mm across. If the magnification on the screen is ×750, what is the actual size of the nucleus?
b) Convert your answer from mm to µm
Answers
a)
b) 0.0033 × 1,000 = 3.3 µm
Question 11
A microscope is using a lens of ×6,000 magnification. If it views a bacteria cell of 5 µm across, how big will its image be in mm and in cm?
Answer

Rearrange to make image size the subject,
Image size = magnification × actual size
Image size = 6,000 × 5 µm
Image size = 30,000 µm
So, in mm the image in mm would be
Or in cm it would be
Question 12
Why do scientists sometimes use a stain such as methylene blue or iodine when looking at cells through a microscope?
Answer
The stain makes some of the organelles in a cell visible, e.g. the cell wall in an onion cell.
Question 13
Describe how you would prepare an onion cell to look at through a microscope in the classroom.
Answer
To make this answer easier to understand I have simplified it by using step-by-step bullet points.
• Peel using tweezers a thin epidermal layer from inside the onion which is nearly transparent.
• Place on a microscope slide.
• Add a drop of iodine stain so the organelles can be clearly seen.
• Lower a cover slip on top of the onion and stain slowly so as to not trap any bubbles.
• Choose an objective lens with the lowest magnification and then using the coarse focus adjust until an image is seen.
• Adjust further with the fine focus to gain a sharp clear image.
• If the image is not satisfactory, change the objective lens to the next highest magnification and repeat the focusing procedure.
PLANT AND ANIMAL CELLS
Plant and animal cells have some organelles in common like a cell membrane, but there are key differences. You will be expected to be able to draw and label each cell, describe what each organelle does and describe the differences between plant and animal cells.
Question 1
What is an organelle?
Answer
An organelle is a ‘structure’ in a cell which has a specific function or job in that cell. This is the same as organs in the body such as the heart which has a function to pump blood around the body.
Question 2
Draw and label a plant cell.
Answer

Question 3
Draw and label an animal cell.
Answer

Note: the animal cell contains a much smaller vacuole, and they are only temporary in animal cells. Depending on the course you study they may or may not be included in the animal cell diagrams, so you should check with your teacher or syllabus if the animal cell diagrams include them as some do and some don’t. It is important to remember however, plant cells always have much larger and permanent vacuole and are always included in all plant cell diagrams whichever syllabi you are following.
Question 4
Name the organelles which perform the following functions,
a) Controls the cell and contains genetic information.
b) A liquid gel where the chemical reactions take place.
c) Where aerobic respiration takes place to release energy.
d) Where proteins are made. (May be called protein synthesis.)
e) Contains chlorophyll and absorbs light.
f) It is filled with sap and supports the cell.
g) Controls the movement of substances into and out of the cell.
h) Made of cellulose and supports and strengthens the cell.
Answers
a) Nucleus
b) Cytoplasm
c) Mitochondria
d) Ribosomes
e) Chloroplasts
f) Permanent vacuole
g) Cell membrane
h) Cell wall
Question 5
What is the difference between a plant and animal cell?
Answer
Generally speaking plant cells have extra organelles which are, chloroplasts, permanent vacuole and cell wall.
Question 6
Why don’t root hair cells contain chloroplasts?
Answer
Chloroplasts contain chlorophyll to absorb light. Because a root is underground there is no light, so they are not needed.
Question 8
The chloroplasts make sugars for food in a plant, in a process which is called what?
Answer
Photosynthesis
Cell differentiation or specialisation
Multicellular organisms like mammals, flowers or even you or I contain different types of cells, all adapted to carry out a particular function (job). Because they have different functions, we say they are ‘specialised’ or ‘differentiated’ to enable them to carry out that function.
You will need to be able to describe how the structure or adaptations relate to the functions of a few plant and animal cells.
Question 1
Draw a labelled diagram of the following animal cells.
a) Sperm cell
b) Muscle cell
c) Nerve cell
Answers



Question 2
For the following descriptions of animal cells say if it is a sperm, muscle or ner