PREFACE
This book is compiled for all aspirant scientists
and teachers young at heart!!!
The CAPS-exam guidelines have been followed.
This book is designed to help students to understand Life
Sciences and make it their own.
To my critical fellow educators:
Do not let the simplicity fool you.
The academic standard was not lowered!!
Compiled by: J Grobler
Published by:
Tel: 074 278 8623 / 084 808 9606
Fax: 086 596 1071
Email: [email protected]
a
Warning!!!
Copyright applies to this publication. In terms of the South African copyright law any
person who copies this publication, or any part thereof, or make copies, commit a crime
and run the risk of being fined or put in jail.
CONTENTS
PAPER I
1. LIFE PROCESSES IN PLANTS AND ANIMALS
1.1 Reproduction in Vertebrates
- Diversity in reproductive strategies
1.2 Meiosis (Also in paper II)
1.3 Reproduction in humans
1.4 The human nervous system
- Central and peripheral nervous systems
- Autonomous nerve systems
1.5 The reflex arc
1.6 Injuries to the nervous system
1.7 The effect of drugs
1.8 Receptors
- The eye
- The ear
1.9 The endocrine system
1.10 Homeostasis
- Negative feed back
- Blood glucose, control of oxygen and carbon dioxide
- Osmoregulation
- Temperature regulation - The human skin
1.11 Plant reaction on the environment
Term
Page
1
167
6
48
60
62
63
67
77
88
98
102
107
2. ENVIRONMENTAL STUDIES
2.1 The impact of humans on the environment
2.2 Water - availability and quality
2.3 Food security
2.4 Loss of biodiversity
2.5 Indigenous knowledge
2.6 Removal of solid waste
116
PAPER II
1
1
1
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
4 - Revise
Mastered
in grade
eleven
Term
3. LIFE ON A MOLECULAR, CELLULAR AND TISSUE LEVEL
3.1
3.2
3.3
3.4
3.5
The structure and functions of the nucleus
DNA - structure, functions and replication
RNA
Protein synthesis
Genetic engineering - Manipulation - Stem cells,
biotechnology and cloning
Mitochondrial DNA, genetic relationships, parenthood and
DNA fingerprinting
146
147
155
156
159
1
1
1
1
1
1
1
1
3. LIFE ON A MOLECULAR, CELLULAR AND TISSUE LEVEL
Page
3.6 Meiosis - Genetic variation, abnormal meiosis
- Differences and similarities between mitosis and meiosis
- Alterations in generations - Moss and ferns
167
3.7 Genetics - Monohybrid and dihybrid crossings
- Sex chromosomes and diseases
- Blood groups
3.8 Mutations
181
2
2
2
2
2
188
191
2
2
200
203
207
224
234
242
246
3
3
3
3
3/4
4
4
176
4. DIVERSITY, CHANGE AND CONTINUITY
4.1
4.2
4.3
4.4
4.5
4.6
4.7
Evolution
Diversity
Early theories on evolution
Evidence of evolution
Evolution of the human
The cradle of mankind
Alternatives for evolution
I
GRAPHS TO BE MASTERED
A.
The line graph
1.
2.
Always add a heading to the graph
The axis (X and Y) must be correctly calibrated (e.g. 2,4,6,8 or 3,6,9,12 etc.)
- You usually have to start with a 0-value
Relative constant values which are called the INDEPENDENT VARIABLES will be found
on the X-axis e.g. temperature, years, time etc. These values are not easily influenced by
external factors
The values on the Y-axis are influenced by external factors such as those found on the xaxis, and are called the DEPENDENT VARIABLES
The unit of the axis must always be indicated
The data on the graph must be shown clearly
3.
4.
3.
4.
X-axis ( Temperature in °C)
20
30
35
40
45
50
Y-axis ( Reaction rate in mg/min)
2
3,5
4,5
5,5
5,5
1,2
Reaction rate
of enzyme
(mg/min)
Temperature (°C)
B. The Pie graph
1. The total area represents 100% or 360°
2. The sum of the segments will equal 100 % or 360°
To calculate the degrees of the circle use:
10
10% = ------- X 360 = 36°
100
20
20% = ------- X 360 = 72°
100
35
35% = ------- X 360 = 126°
100
II
C.
The Histogram
1.
2.
3.
4.
Data is represented by individual columns for comparison
A series of data is shown for example ages 5-10, 10-15, 15-20 etc.
The columns touch and are of equal width
The axis must be correctly calibrated
Number of
deaths
Age at death (years)
D. The bar / column graph
1.
2.
The bar graph has spaces between the columns
Each column represents something different, and no series is formed
Composition
(%)
KEY:
1
PAPER I
LIFE PROCESSES IN PLANTS AND ANIMALS
1. Reproduction in vertebrates
- Diversity in reproductive strategies
2. Meiosis
3. The human nervous system
4. Receptors
5. The endocrine system
6. Homeostasis
Page 167-175
To Contents
2
REPRODUCTION IN VERTEBRATES
Diversity of animals’ reproductive strategies
1.
2.
Reproductive strategies can be regarded as sexual behaviour that increases
reproductive success in different environments
Animals have different behaviours during reproduction, to reproduce successfully to
ensure their specie’s survival
DIFFERENT REPRODUCTIVE STRATEGIES IN NATURE
A.
COURTSHIP BEHAVIOUR
1.
2.
Male birds differ from female birds
Male peacocks spread their tail feathers, ostriches perform mating dances, doves
parade, etc.
Frogs and crickets call each other at night time to mate
Rituals usually take place where the male tries to impress the female!
- (That is why grade 12 boys gym!!)
Chemical substances known as pheromones are secreted; the pheromones attract the
opposite sex e.g. elephants, antelope etc.
Courtship behaviour is used to find the best partner with the best genetic material.
- this ensures a specie’s survival
3.
4.
5.
6.
B.
EXTERNAL FERTILISATION
1.
3.
4.
5.
6.
Many aquatic aminals like fish and frogs use
- water during reproduction
The male frog will hold on to the female
- to stimulate her to lay eggs
The male releases his sperm once the female lays her eggs
Fertilisation therefore occurs externally in the water
The advantage of external fertilisation is the huge amount of eggs that can be laid
The disadvantage is that many eggs are lost or are not fertilised successfully
C.
INTERNAL FERTILISATION
1.
Internal fertilisation occurs in all terrestrial organisms
2.
Some aquatic species also have internal fertilisation,
e.g. whales, dolphins, marine turtles etc.
The male organism has a copulatory organ / penis
that releases sperm in the female organism
The advantage of internal fertlisitation is the
increased chances of fertilisation
The embryo is protected and nourished
- inside the female’s body
2.
3.
4.
5.
3
D.
OVIPARITY
1.
It is a reproduction method where eggs
- are laid by the female organism and
- the embryo develops outside her body
Most reptiles, fish, amphibia and all birds are oviparous
Parental care is usually absent except in
- e.g. crocodiles and pythons
Yolk inside the fertilised eggs provides the embryo with carbohydrates and fats
Albumin (egg white) provides the embryo with water and proteins
The advantage of being oviparous is that a huge amount of eggs that can be laid; the
eggs can develop independently without parental care
The disadvantage of being oviparous is that many eggs are lost to predators and weather
conditions such as unfavourable temperatures, dry conditions etc.
2.
3.
4.
5.
6.
7.
E.
VIVIPARITY
1.
It is reproduction where the embryo develops
inside the female organism’s uterus
The embryo is fed by a placenta and umbilical cord
from the mother’s blood stream
Most mammals and human beings are viviparous
There is usually parental care after birth and
the youngsters are suckled (lactation with milk)
The advantage of being viviparous is that the embryo
is protected and nourished inside the mother,
which increases the embryo’s chance of survival
The disadvantage of being viviparous is
that fewer offspring can be produced
2.
3.
4.
5.
6.
F.
OVOVIVIPAROUS
1.
It is reproduction where the egg
- develops and later hatches inside the female’s body
It appears as if the young are born “living”like mammals!
Yolk inside the egg nourishes the embryo, since
no placenta connects the mother and the embryo
Big sharks and snakes such as puff adders
are ovoviviparous
There is no parental care and the young are
self-sufficient once they have hatched
The advantage is that the embryos stay protected
inside the female’s body until the eggs are hatched
The disadvantage is that fewer eggs can be produced,
because it has to stay inside the female’s body
2.
3.
4.
5.
6.
7.
4
G.
THE AMNIOTIC EGG
A LONGITUDINAL SECTION THROUGH THE AMNIOTIC EGG
1.
2.
3.
4.
5.
6.
7.
8.
The amniotic egg is found in birds
The embryo lies inside a fluid-filled amnion surrounded by an eggshell
The eggshell prevents the egg from drying out and protects it in different habitats
The yolk inside the fertilised eggs provides the embryo with carbohydrates and fats
Albumin (egg white) provides the embryo with water and proteins
Waste products are stored inside the allantois
Gaseous exchange occurs through the porous shell.
Oxygen diffuses into the egg’s air bubble. The diffusion of oxygen and carbon dioxide is
controlled by the chorion
THE HARVESTING OF EGGS FOR HUMAN CONSUMPTION
1.
2.
3.
4.
5.
Humans use laying hens for intensive egg production, since eggs are an important source
of food
This can be very cruel, because the hens are kept in very small cages and are
mechanically fed under artificial lights
Unfertilised eggs are laid
A hen’s production decreases after two years and then she is slaughtered
The new, modern trend is free roaming hens being fed properly during normal daylight
hours. The eggs are then collected where they are laid (not so cruel!)
H.
PRECOCIAL DEVELOPMENT
1.
Domesticated chickens, ducks,
- ostriches and geese show precocial development since the
- chicks leave the nest which is on the ground within two days
The incubation period inside the egg is long and the chicks are
- highly developed when they hatch
Their eyes are open and they are covered with down
- They can also walk well
2.
3.
4.
5.
6.
5
Bush turkeys can fly and provide for themselves immediately once they have hatched!
Ducklings and chicks follow their parents, but find their own food
The advantage of precocial development is that the young can escape predators easily
and are more independent
I.
ALTRICIAL DEVELOPMENT
1.
This development occurs in birds that nest
- high in trees
The egg’s incubation period is short and the
- young are not well developed when they hatch
Their eyes are closed and they hardly have
any feathers
Parental care is very important for survival,
because they have to be fed constantly
- and must be kept warm
They stay in the nest for a long time
The disadvantage of altricial development is
that the chicks are vulnerable to predators and
starvation if they are not taken care of by their parents
2.
3.
4.
5.
6.
J.
PARENTAL CARE
Parental care can occur as follows:
1.
2.
3.
4.
5.
6.
Through building nests and digging holes where the
young are protected and fed
- Even mammals such as wild dogs and hyenas
- bring up their young in holes under ground
- This protects the young against predators
By caring for the eggs
- Pythons and crocodiles protect their eggs and
- also help the eggs to hatch
- Birds protect and care for their eggs in nests
- The eggs are often turned and predators are driven away
Through providing nourishment to the unborn or unhatched young
- Dung beetles roll balls of dung under ground on which the eggs are lain
- Wasps sting and lame caterpillars and spiders which serve as food for their larvae as
soon as they hatch. Mammals have placentas through which unborn young are nourished
Through the provision of food for young after they were born or hatched
- The young of mammals are suckled
- Birds regurgitate half-digested food for their young
- African wild dogs also regurgitate meat for their young after a hunt
By protecting the young directly
- The young can ride on its mother’s back or tail and is protected against predators
- Apes and baboons are perfect examples.
- Even hatchlings of swans ride on their parents’ backs
Through social assistance until the young are mature and independent
- Young elephant cows stay with their mothers to learn social behavior.
- All primates do the same. A chimpanzee in confinement does not know how
- to suckle its young, and has to be taught
6
HUMAN REPRODUCTION
LIFE CYCLE OF HUMANS
MEIOSIS
FERTILIZATION
MITOSIS
SEXUAL CHARACTERISTICS
1.
Primary characteristics:
- These are responsible for the reproduction and fertilisation process
- These are the sexual organs with which boys and girls are born!
2.
Secondary characteristics:
- These are responsible for making opposite sexes attractive
- These characteristics only appear during puberty
- e.g breasts in girls, pubic hair, facial hear in boys etc.!!
THE MALE REPRODUCTIVE SYSTEM
It consists of three main parts:
1.
2.
3.
Organs responsible for the production of spermatozoa / sperms
- namely the 2 testes (testis = 1)
Organs responsible for the storage and transport of the spermatozoa
- namely the epididymis, vas deferens, seminal vesicles and the urethra.
- The prostate gland and Cowpers gland also play a role
The organ responsible for transferring the spermatozoa, the penis
To Contents
7
THE STRUCTURE OF THE MALE REPRODUCTIVE SYSTEM
A. Front view (internal)
Ureter
Bladder
Vas deferens
Ampulla
Seminal vesicle
Ejaculatory duct
Prostate gland
Cowper gland
Penis
Urethra
Head of the Epididymis
Testis
Scrotum
Tail of the Epididymis
B. Side view (internal)
Ureter
Vas deferens
Bladder
Seminal vesicle
Ampulla
Prostate gland
Ejaculatory duct
Cowper gland
Head - epididymis
Tail - Epididymis
Testis with lobes
Corpora cavernosa
Corpus spongiosum
Urethra
Penis
Glans penis
Foreskin
8
A. THE STRUCTURE OF THE TESTES
Longitudinal
cross section
through the testis
Head - Epididymis
Septum
Seminiferous
tubule
Lobe
Scrotum
Rete testis
Tail - Epididymis
Connective tissue
Vas deferens
Cross section through the seminiferous tubule
1.
2.
3.
4.
5.
6.
7.
In the embrionic stage of a boy, the testes are located in the abdominal cavity below the
kidneys
Shortly before birth, the testes move through the spermatic cord and settle into an
external sac called the scrotum outside the body cavity
The spermatic cord consists of the
- vas deferens, nerves
- spermatic artery and vein, lymph vessels
Two testis, enclosed with connective tissue
- Each divides into 300 lobes which are separated through septa (singular = septum)
Each lobe consists of 1-3 convoluted seminiferous tubules
All these tubules measure a length of about 500m!
The seminiferous tubules connect with the rete testes (larger tubules) which connect to
- a large convoluted tube, the epididymis
8.
9.
9
The seminiferous tubules are lined with germinal epithelium cells
- which consist of spermatogonium and sertoli cells
Spermatogonium cells are diploid (2n) and give rise to spermatozoa / sperm (n)
- during spermatogenesis (meiosis)
- Sperm cells are embedded with their heads into the sertoli cells
FUNCTIONS OF THE SERTOLI CELLS
1.
Supply food to the spermatozoa
2.
Produce fluids that help the sperm to move
3.
Cells of Sertoli form the Sertoli border and prevent the transportation of
- dangerous chemicals from the blood to the testes
FUNCTIONS OF THE LEYDIG CELLS
1.
Interstitial cells / cells of Leydig are endocrine cells that are responsible for the
production of testosterone (the male hormone)
THE FUNCTION OF THE SCROTUM
1.
The scrotum serves as a temperature regulator
- It keeps the testes at a lower temperature than the body temperature, which is
- necessary for the production of sperm
2.
A layer of smooth muscles in the scrotum contracts when it is cold and pulls the
testes closer to the body
3.
When it is warm, the muscles relax to allow the testes to hang farther from the
body
WHAT IS THE FUNCTION OF TESTOSTERONE?
1.
2.
3.
6.
It activates and maintains spermatogenesis (the formation of sperm cells)
It develops and maintains the male reproductive organs
It is responsible for the development of male secondary characteristics
- such as deepening of the voice, growth of pubic and facial hair
It stimulates protein anabolism (growth) and bone growth
It is responsible for sexual vitality and aggression
(NOT AN EXCUSE FOR BAD BEHAVIOR!!)
It stimulates an increase in the production of red blood corpuscles
B.
THE EPIDIDYMIS
1.
It is a convoluted tube, approximately 5m long
- which is located inside the scrotum, but outside the testes
It is lined with germinal epithelium
It consists of three parts:
- the head which is closest to the testes
- the body and
- the tail
The immature sperm cells are transported from the testes into the head of the
epididymis
4.
5.
2.
3.
4.
10
FUNCTIONS OF THE EPIDIDYMIS
1.
4.
The sperm cells mature inside the epididymis while moving from the head to the
tail
The epithelium of the epididymis secretes a fluid which
- facilitates the transportation of the sperm cells
The transportation is made possible by peristaltic waves which are caused by the
- contraction and relaxation of muscle fibres in the epididymis
Sperm are also stored in the epididymis until ejaculation takes place
C.
THE VAS DEFERENS
1.
2.
It is the continuation of the epididymis
It stretches from the tail of the epididymis and leaves the scrotum
- via the spermatic cord
Before the vas deferens connects with the neck of the bladder, a widening is
- formed which is called the ampulla
It connects with the ejaculation tube which widens in the urethra
2.
3.
3.
4.
Functions of the vas deferens:
1.
2.
It transports the mature sperm from the epididymis into the urethra
The layer of smooth muscle is responsible for the strong peristaltic waves
- during ejaculation
D.
THE URETHRA
1.
2.
3.
5.
The urethra is found inside the penis
It is the canal used for transportation of urine and sperm (never at the same time)
Contractions of smooth muscle layers transport the sperm and urine (from the
bladder) to the urethra
Moisture secreted by the epithelium of the
- ampulla, vas deferens and ejaculation tube
- as well as secretions from the prostate gland and Cowper’s gland
- enhances the movement of the sperm
Moisture + sperm cells = semen
E.
THE SEMINAL VESICLE
1.
2.
It consists of two sac-like structures between the bladder and the rectum
Their walls are lined with a mucous membrane
- which secretes a sticky, yellowish, slimy mucus
- which forms part of the seminal fluid
4.
11
Functions of the seminal vesicle / seminal fluid
The seminal fluid contains:
1.
Globulin and fructose sugar = supplies the sperm with energy to swim
2.
Prostaglandin
- stimulates contractions in the urethra
- makes the mucus more liquefied in the opening of the uterus of the woman
- and causes reversed peristalsis in the uterus to help the sperm cells
3.
Fibrinogen – forms a temporary plug in the vagina after an ejaculation
4.
Seminal fluid is alkaline – this neutralizes acids in the urethra and vagina
F.
THE EJACULATORY DUCT
1.
The duct of the seminal vesicle and
- the ampulla of the vas deferens connects with the ejaculatory duct
The ejaculatory duct runs through the prostate gland and
- connects with the urethra
2.
G.
THE PROSTATE GLAND
1.
2.
The prostate gland is normally the size of a walnut
It is found leaning against the bladder
- and surrounds the urethra
The prostate gland consists of glandular tissue imbedded
- in smooth muscle tissue
The smooth muscles contract with an ejaculation and
- forces the prostate fluid into the urethra
- through twelve to twenty small ducts
3.
4.
Functions of the prostate gland
1.
2.
3.
The prostate fluid makes up one third of the semen
The prostate gland secretes a milky liquid
- and is responsible for the particular smell of semen
It activates the sperm cells
H.
THE PENIS
1.
2.
3.
The penis serves as a copulation organ during sexual intercourse
The penis consists of three different cylinders of expandable tissue
Two rods, the corpora cavernosa, are located on the upper side
- next to each other over the length of the penis
The third part is the corpus spongiosum
- which surrounds the urethra, ventral to the corpora cavernosa
The tip of the penis is called the glans penis and is covered by the foreskin
In some religions and cultures, the foreskin is removed in early childhood or
puberty - This process is called circumcision
4.
5.
6.
12
WHAT IS AN ERECTION?
1.
During an erection the penis becomes firm and erect
- as a result of an increase in blood flow into the penis
The muscles that surround the connection of the
- corpora cavernosa and the corpus spongiosum, contract and
- delay the blood flow in the veins to keep the erection
An erection is necessary for successful sexual intercourse
2.
3.
Impotence is frequently found in older men
- An erection can’t occur
- It is often caused by being over weight, heart diseases, etc.
I.
THE COWPER’S GLANDS
1.
It consists of two small glands
2.
- one on each side of the urethra
- beneath the prostate gland
It is connected to the urethra with short ducts
Functions of the Cowper’s gland:
1.
2.
3.
It secretes a clear alkaline mucus
- which serves as a lubricant during sexual intercourse
It protects the sperm cells by neutralizing the acids in the urethra
It activates the sperm cells to greater mobility
WHAT IS SEMEN? - THE COMPOSITION OF SEMEN
1.
2.
3.
Semen consists of sperm cells + seminal fluids
- from the prostate gland, Cowper’s gland, seminal vesicle, etc.
One ejaculation consists of 2.5 to 5ml of semen
- with 50 – 150 million sperm cells per ml.
- Thus, one ejaculation contains 700 million sperm cells!!
A sperm cell count of less than 20 million per ml, is a sign of infertility!
What causes a low sperm cell count?
1.
2.
3.
4.
5.
Toxins in the environment
Antibiotic substances such as Tetracycline
Smoking cigarettes and weed / dagga
Alcohol
Tight clothing overheats the testes which reduces the sperm count
13
FUNCTIONS OF SEMEN
1.
2.
3.
4.
5.
6.
7.
Semen serves as a transportation medium for the sperm cells
- to be able to move through the female reproductive system
Fructose sugar and globulin provide food for the sperm cells
Alkaline fluid (pH = 7.2 – 7.6) neutralizes the acids in the vagina
Enzymes activate sperm cells to greater mobility
Prostaglandins liquefy the thick, sticky slime of the cervix and
- causes reversed peristalsis in the uterus
Antibiotics destroy bacteria to protect the sperm cells against infection
Mucus serves as a lubricant during sexual intercourse
DISEASES OF THE MALE REPRODUCTIVE SYSTEM
1.
Prostatic
- Inflammation in the prostate is caused by bacteria
Inflammation - The symptoms are similar to prostate cancer
- The person complains of pain in the lower back and rectum
- Urinating is painful; the prostate gland becomes swollen and
- closes up the urethra. It is treated with antibiotics
2.
Prostate cancer
- It is very commonly found in older men and is very
- dangerous
- Urinating is painful and difficult because the prostate
- gland becomes swollen and blocks the urethra
3.
Impotence
- The man struggles to get and keep an erection
- It is caused by poor blood circulation,
- heart disease and over weight
4.
Low sperm count and infertility: A sperm analyses determines the man’s fertility
Analysis
1. Volume of semen
2. Sperm count
3. Mobility of the sperm
Test result
There is supposed to be 25ml of semen per
ejaculation
There is supposed to be at
least 60 million sperm cells
per ml.
At least 60% of the sperm
cells must be active
4. Shape of the sperm
At least 60% of the sperm
cells must be normal
5. The Hamster test!
Normal sperm cells would
impregnate a hamster’s
ovum! No further growth will
take place.
Problem
Less suggests inflammation
in the prostate gland or
seminal vesicles
Less suggests inflammation
in the epididymis, vas
deferens or prostate gland
Is caused by genetic
disorders, smoking, drugs,
etc.
Is caused by genetic
disorders, smoking, drugs,
etc.
If fertilization doesn’t take
place, the sperm cells may
have abnormal acrosomes
14
SUMMARY OF THE STRUCTURES OF THE MALE REPRODUCTIVE SYSTEM
STRUCTURE
1.
Testes
Testis = singular
2.
Scrotum
3.
Epididymis
FUNCTIONS
1. Sperm cells are produced during spermatogenesis
2. Leydig cells produce testosterone which
- activates and maintains spermatogenesis
- maintains male reproductive organs
- maintains secondary sexual characteristics
3. Cells of Sertoli form the Sertoli border which
- protects and feeds the sperm
- secretes fluid which is found in
- the seminiferous tubules
1. Surrounds the testes
2. Necessary for temperature regulation
3. Contracts when cold
4. Relaxes when warm
1. Sperms move from the testes to the epididymis
2. Sperms mature as they move along
3. Fluids from the mucous membrane help movement
4. Mature sperms are stored in the epididymis
4.
Vas deferens
1. Sperms move upwards in the vas deferens
2. The ampulla contracts to push the sperm to the urethra
3. Strong peristalsis is involved during an ejaculation
5.
Prostate gland
1. Secretes an alkaline fluid
2. Fluid has a characteristic smell
3. Provide 20 – 30% of the seminal fluid
4. Activates the sperm cells to greater mobility
1. Produces 60% of the seminal fluid and contains:
2. Fructose sugar and globulin – energy for sperm cells
3. Prostaglandin
- stimulates contractions in the urethra
- stimulates reversed peristalsis inside the uterus
- liquefies the mucus of the cervix
4. Fibrinogen – forms a temporary plug in the vagina after
- an ejaculation
Seminal fluid is alkaline and neutralizes acids in the
Vagina
6.
Seminal vesicle
7.
Cowper’s glands
8.
Penis
1. Secretes a sticky, alkaline mucus (slime) – promotes
mobility of sperms
2. Mucus serves as a lubricant during sexual intercourse
3. Alkaline liquid neutralizes acids in the urethra
1. Serves as a copulation organ
2. Transports semen through the urethra during ejaculation
15
GAMETOGENESIS
Gametogenesis is the process in which mature gametes are formed in the gonads
1.
2.
Spermatogenesis is the production of sperm cells in the testes
Oogenesis is the production of a mature ovum in the ovaries
1.
2.
3.
Both processes require meiosis to change 46 chromosomes into
- 23 in the gametes
Sperm cells / spermatozoa and ova are haploid (n)
After fertilisation the zygote is diploid (2n) with 46 chromosomes
SPERMATOGENESIS
1. Spermatogenesis begins at puberty (1415 years old)
2. The hormone ICSH / LH from the
pituitary gland
- stimulates secretion of
- testosterone in the testes
- which in turn stimulates spermatogenesis
3. Spermatogonia in the sperm tubules are
diploid (2n) with 46 chromosomes each
4. Spermatogonia undergo mitosis and
form more spermatogonia
5. Spermatogonia become mature and form
primary spermatocytes
6. The primary spermatocyte undergoes the
first stage of meiosis and forms two
secondary spermatocytes with 23
chromosomes each
7. The secondary spermatocytes
undergo the second stage of meiosis
and forms four round spermatids
8. Spermatids are immature and must still
develop into haploid (n) spermatozoa
9. The duration of Spermatogenesis is
approximately 72 days
10. The spermatozoa mature inside the
Epididimus (Mature sperm cells have tails
for swimming)
Mitosis
Spermatogonium
cell (2n)
(2n)
Primary
spermatocyte
(2n)
Meiosis I
Secondary
spermatocyte
Meiosis II
Spermatids (n) develop into spermatozoa
16
STRUCTURE OF THE SPERM CELL
Acrosome with hydrolytic
enzymes
Outer membrane
HEAD
Nucleus (n) with
23 chromosomes
Centriole which starts
meiosis II after fertilisation
Mitochondria - in helix shape
NECK
MIDDLE
PIECE
Transverse section
Fibres
Mitochondria
TAIL
1.
2.
3.
Inner fibres
Central fibres
The mature sperm cell consists of a head, neck and tail
The head contains an acrosome and the nucleus
The nucleus contains 23 chromosomes and is haploid
STRUCTURAL ADAPTATIONS OF THE SPERM TO ENSURE FERTILIZATION
1.
2.
3.
4.
The acrosome has hydrolytic enzymes which is responsible for
- digesting the outer layer of the secondary ovum during fertilisation
The neck contains many mitochondria which provide energy
- to the sperm during cellular respiration
Sperm must swim through the cervix, to the Fallopian tubes for fertilisation
- The tail / flagellum contains fibres that help the sperm to swim
The centriole makes Meiosis II possible in the ovum after fertilization occurred
17
ACTIVITY
1.
Study the diagram of the sperm and answer the following questions:
1.1
1.2
1.3
1.4
1.5
Identify the regions A to C (3)
Identify the parts 1 to 3 (3)
What is the function of number 2? (1)
Is the contents of number 2 haploid or diploid? (1)
Number 1 contains enzymes.
Shortly describe the function of these
enzymes during fertilization (2)
Part B contains many mitochondria. Why? (2)
What is the function of the sentriole? (2)
1.6
1.7
2.
Study the diagram of the male reproductive system and answer the following
questions:
2.1
2.2
2.3
2.4
2.5
Identify number 1 to 10 (10)
Which process takes place in number 9? (1)
What is the function of number 10? (1)
In which part does the sperm mature? (1)
To which organ is number 10 connected? (1)
2.6
Write down two functions of each of the glands
shown in:
a) number 2
b) number 5
c) number 3 (6)
2.7
Identify and describe the process which takes
place in number 9 (10)
Through which process are the sperms
transported in number 7? (1)
In which part is cancer likely to form? What are
the symptoms if cancer is present? (4)
2.8
2.9
3.
Study the diagram of the dividing process in the testes and answer the questions:
3.1
3.2
3.3
3.4
What is this process called? (1)
Which process takes place from number 1 to 2? (1)
Which process takes place from number 2 to 3? (1)
Where in the male reproductive system do
the sperm mature? (1)
How are the sperm fed? (2)
Which hormone controls this division process? (1)
Which structure (number) in the drawing
is diploid? (1)
Which structures (numbers) are haploid? (2)
3.5
3.6
3.7
3.8