Download Everything Life Sciences Grade 10 PDF

TitleEverything Life Sciences Grade 10
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LanguageEnglish
File Size18.0 MB
Total Pages345
Table of Contents
                            Life Sciences Grade 10 cover ENG
Front matter 1
Life Sciences Grade 10 contributors
Life Sciences mutual pages
LifeScienceGr10-Learner
	Introduction to Life Sciences
		About this chapter
		What is Life Sciences?
		Why study Life Sciences?
		How science works
		Biological drawings and diagrams
		Tables
		How to draw graphs in Science
		Mathematical skills in Life Sciences
		Lab safety procedures
	The chemistry of life
		Overview
		Molecules for life
		Inorganic compounds
		Organic compounds
		Vitamins
		Recommended Dietary Allowance
		Summary
	The basic units of life
		Overview
		Molecular make up of cells
		Cell structure and function
		Cell organelles
		Summary
		End of chapter exercises
	Cell division
		Overview
		The cell cycle
		The role of mitosis
		Cancer
		Summary
		End of chapter exercises
	Plant and animal tissues
		Overview
		Tissues
		Plant tissues
		Animal tissues
		Applications of indigenous knowledge and biotechnology
		The leaf as an organ
		Summary
	Support and transport systems in plants
		Overview
		Anatomy of dicotyledonous plants
		Transpiration
		Uptake of water and minerals in the roots
		Summary
	Support systems in animals
		Overview
		Skeletons
		Human skeleton
		Musculoskeletal tissues
		Human locomotion
		Muscle structure and function
		Diseases
		Summary
	Transport systems in animals
		Overview
		Circulatory systems in animals
		Lymphatic circulatory system
		Cardiovascular diseases
		Summary
	Biospheres to ecosystems
		Overview
		Biosphere
		Biomes
		Environment
		Ecosystems
		Energy flow
		Nutrient cycles
		Ecotourism
		Summary
	Biodiversity and classification
		Overview
		Biodiversity
		Classification schemes
		Five kingdom system
		Summary
	History of Life on Earth
		Overview
		Representations of life's history
		Life's History
		Mass extinctions
		Impact of humans on biodiversity and environment
		Fossil tourism
		Summary
                        
Document Text Contents
Page 1

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GRADE 10 GRADE 10

WRITTEN BY VOLUNTEERS WRITTEN BY VOLUNTEERS

VERSION 1 CAPS VERSION 1 CAPS

LIFE SCIENCES LIFE SCIENCES

EVERYTHING SCIENCE
BY

MEDULLA OBLONGATA:
Takes care of your body’s
vital functions, like breathing
on your behalf, while you
study this book.

CEREBELLUM:
Raises your hand
at the exact time
you have a question
about this book.

FRONTAL LOBE:
Decides when you
will study for your
exam and makes
you feel happy
when this book
has helped you
pass a test.

PRIMARY SENSORY CORTEX:
Judges the texture of this book
to let your hands know they’re
holding paper.

OCCIPITAL LOBE:
Processes the
visual information
of this book.

PARIETAL LOBE:
Turns the letters of this
book into words, and those
words into thoughts.

TEMPORAL LOBE:
Hears your teacher’s
voice and processes it
so you can remember
what was said in class.

PRIMARY MOTOR CORTEX:
Moves your body to the
bathroom when you take
a break from this book.

EVERYTHING LIFE SCIENCES

PONS:
Chooses whether
you’ll doze off
or stay awake
in class while
being taught
from this book.

BROCA’S AREA:
Allows your facial
muscles to form
a frown when you’re
trying to solve a
problem in this book.

SPINAL CORD:
The highway that is busy
channelling the signals
between your body
and brain as we speak.

Don’t break your brain over
this one, it’s just a piece of paper.

THIS TEXTBOOK IS AVAILABLE
ON YOUR MOBILE

Everything
Science

This book is available on web, mobi and Mxit.
Read, practice intelligently or see solutions at m.everythingscience.co.za

ISBN 978-1-920423-91-9

9 7 8 1 9 2 0 4 2 3 9 1 9

2436_SIYAVULA_GRADE 10_LIFE SCI_FA.indd 1 2012/11/12 5:03 PM

Page 2

EVERYTHING SCIENCE

VERSION 1 CAPS

WRITTEN BY VOLUNTEERS

GRADE 10 LIFE SCIENCES

Page 172

Figure 6.10: Stem showing internode and nodes plus leaf petioles.

Figure 6.11: Photo of a redwood. The trunk of the tree is its stem.

The internal structure of the dicotyledonous stem

Figure 6.12 shows a schematic arrangement of tissues in a dicotyledonous stem. Details of
each tissue type are described in this section.

Epidermis: a single layer of cells that covers the stem, and is in turn covered by a waxy
cuticle. The waterproof cuticle helps prevent water loss and thus prevents the inner tissues
drying out. Since the function of the epidermis is to protect underlying tissues, epidermal
cells are tightly packed and have thickened walls. The epidermis may contain hair-like out-
growths known as trichomes, and stomata with guard cells. Stomata present in the epidermis
allow for gaseous exchange for respiration and photosynthesis.

Cortex: a region which comprises of collenchyma, parenchyma and the endodermis

• Collenchyma: a few layers of living cells that lie under the epidermis. These cells
are not lignified but do have thickened cell walls which serve to strengthen the stem.
The collenchyma cells contain chloroplasts which produce food for the plant during
photosynthesis.

• Parenchyma: found beneath the collenchyma cells and makes up the bulk of the cor-
tex. The cells are thin-walled, and there are intercellular spaces which are important
in gaseous exchange. Parenchyma stores synthesised organic food (mostly starch) that
the collenchyma produced.

• Endodermis: a single layer of tightly-packed rectangular cells that forms the innermost
layer of the cortex. The endodermis also stores starch and, as the border between the
stele and cortex, regulates the passage of solutions from the vascular bundles to the
cortex.

164 6.2. Anatomy of dicotyledonous plants

Page 173

Layer 7


epidermis

epidermal hair

collenchyma of the cortex

pith (parenchyma)

cortex (parenchyma)

endodermis

xylem

sclerenchyma of the vascular bundle

cambium vascular bundle

Cross-section of a Dicotyledonous Stem

phloem

medullary ray
(parenchyma cells in gaps
between vascular bundles)

Figure 6.12: Cross-section of a dicotyledonous stem showing tissue distribution.

Vascular cylinder or stele: comprised of the pericycle, vascular bundles and pith

• Pericycle: made up mainly of lignified, dead, fibrous cells known as sclerenchyma
cells. Sclerenchyma cells have end-to-end connections (tapering ends), and have ex-
tremely thick walls that consist of lignin and/or cellulose. These thickened, woody cell
walls are very hard and play an important role in strengthening the stem, and providing
protection for the vascular bundles.

• Vascular bundles: characteristically organised in a ring inside the pericycle of the di-
cot plant. Mature vascular bundles are made up of water-conducting xylem, cambium,
and food-conducting phloem. The phloem is located on the outside of the bundle and
the xylem towards the centre (see Figure 6.12). The phloem and xylem is separated by
meristematic tissue known as cambium, which is responsible for secondary thicken-
ing. Xylem has lignified cell walls which helps it fulfil its two important roles, namely;
strengthening and supporting the stem, and transporting water and minerals from the
root system to the leaves. The function of phloem is to transport synthesised food from
the leaves to other parts of the plant.

• Pith (or medulla): occupies the large, central part of the stem. The pith is made up of
thin-walled parenchyma cells containing intercellular spaces. Where the parenchyma
extends between vascular bundles as thin bands it is known as medullary rays, and
can be continuous with the pith and cortex of the parenchyma. The cells of the pith
store water and starch, while the intercellular spaces allow for gaseous exchange. The
medullary rays facilitate transport of substances from xylem and phloem to the inner
and outer parts of the stem.

Investigation: Examining the structure of the root and stem

Aim:

To examine the structure of the root and stem

165Chapter 6. Support and transport systems in plants

Page 344

• It takes special circumstances for fossils to form, and fossils can be dated by radiometric
dating.

• Climate and geography helped shape the evolution of life on Earth.
• Geological timescales are divided into eons, eras and periods.
• The Cambrian explosion, was a rapid explosion in the diversity of life-forms. All animal

groups have their origin in the Cambrian explosion.

• During the Paleozoic the first fish, animals with shells and insects evolved and plants
first colonised land.

• The Mesozoic was the ‘age of dinosaurs’, later in the era birds evolved, and gym-
nosperms evolved.

• The Cenozoic is the most recent era and was the ‘age of mammals’.
• Mass extinctions are massive losses in life, and there have been five mass extinction

events in history.

• In the last 4 million years significant changes have occurred in species occurring in
Africa, including the evolution of humans.

• Humans have a massive effect on biodiversity and the natural environment and are
partially responsible for the ’6th mass extinction’.

• South Africa is rich in many fossils from diverse time periods.
• Fossil tourism is a source of income and employment in fossil localities.

Exercise 11 – 1: End of chapter exercises

1. In each of the following cases write down the letter of the most correct alternative.

a) Which of the fossils have been found in Namibia?

i. Mammal-like reptiles

ii. Glassopteris leaves

iii. Soft-bodied animals

iv. Early mammals

b) What was the importance of stromatalites

i. They released oxygen into the air

ii. They absorbed oxygen and prevented animals getting poisoned

iii. They are the closest ancestors of modern plants

iv. They were algae trapped in sediment

c) A problem in determining the accuracy of radiometric dating is that

i. scientists are not sure that radioactive decay actually occurs

ii. the decay rate of minerals can change without warning

iii. the rocks that contain the fossils can’t be dated

iv. only organic samples can be dated radiometrically

2. Essay:

• The Cradle of Humankind World Heritage site has numerous tourism and eco-
tourism attractions. These ecotourism attractions include the Sterkfontein Caves,
the Wonder Caves, the first gold mine in Gauteng, rock art sited and as many
game reserves.

• You are to write an essay of approximately 1 to 1
1

2
pages promoting one of these

336 11.7. Summary

Page 345

World Heritage Sites as a tourist attraction. You will be given time to research
your chosen heritage site at home and then the essay will be written in class under
examination conditions. You will only be permitted to bring along a concept map
with details of your heritage site.

3. Study the table below that shows the decay of carbon-14 over time and then answer
the questions that follow:

Decay of carbon-14
Years
from

present

0 5 730 11 460 17 190 22 920 X 34 380 40 110

Number
of

half-lives
elapsed

0 1 2 3 4 5 6 7

Percentage
of

original
carbon-

14
remaining

100 50 25 12,5 6,25 Z 1,56 0,78

� State TWO types of methods used to determine the age of fossils.
� Calculate the value of

– X
– Z

Explain why it would not be possible to date a fossil which existed 80 million
years ago using the decay of carbon-14.

�� Give TWO reasons why there are gaps in the fossil record.

4. Study the graph below which shows the major extinction events answer the questions
that follow.

� When did the Cenozoic era begin?
� Which mass extinction took place towards the end of the
� Paleozoic era?
� Approximately how many families of species went extinct at the end of the Pale-

ozoic era? Show ALL working.

� Explain why the number of families of organisms, after each mass extinction
rapidly increased.

� The following questions are about the extinction of dinosaurs on Earth.
� What evidence do scientists use to show that dinosaurs once existed on Earth?
� How long ago did the dinosaurs become extinct?
� Describe a hypothesis that has been proposed for the extinction of many species,

including the dinosaurs during the extinction event at the end of the mesozoic.

337Chapter 11. History of Life on Earth

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