Chapter 1 Grade 8 Odd Semester

1. GROWTH
and
DEVELOPMENT
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2. a. The Definition
• Growth constitutes an increase process in
size including increases in height, and
weight. Growth is quantitative and
irreversible in nature
• Development is a process towards
maturity. Development is qualitative in
nature, meaning that it is immeasurable
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3. b. GROWTH and DEVELOPMENT in
THE PLANTS
• Plant growth occurs because of the size increase
which is caused by the increase in the number
of cells through cell division (mitosis) in the
growing points and enlargement in each cell
• Cell division mostly occurs in the meristem
tissue, that mostly found in the root tip and
stem tip which are called apical meristem
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4. • When the young plants grow, the root and
the stem grow longer, this growth is called
primary growth
• Some plants, such as wooden plants, have
stems and roots which become thicker, this
growth is called secondary growth
• To measure the speed growth of plants, we
use the auxanometer
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5. • The development of seed plants which reproduce
through the generative method starts with a zygote
• The zygote grows into embryo then become an
individual which posseses roots, stems, and leaves.
• After reaching a certain age, the plants will produce
flowers and seeds
• The changes of shape and function from one zygote
until the plant is forming root, stem and leaf organ is
called the development process of plants
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6. Factors Which Affect Plants Growth
And Development
• Internal Factors
a. Genes
- the size and shape of plants are affected by
the genes inside the chromosomes
- Chromosomes are found in the nucleus
- Genes are derived from the parents
- Genes control the growth pattern of the
plants
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7. b. Hormones
- A hormones is a chemical subtance which
is produced by plants, are often called
growth subtances
- Its function is to control the growth
process
- the common growth hormones are auxin,
cytokinin, and gibberellin
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8. 1. Auxin
- Auxin is produced in the stem tip (bud), young leaves,
flowers, fruit, and root tip
- Auxin which found in the stem tip can inhibit the
growth of branches, this condition is called apical
dominance. Therefore the plants can grow tall and
straight.
- The effects of auxin are :
 to stimulate the lateral roots and fibrous roots growth
 to stimulate the growth of stem cells and inhibit the
growth of root cells
 to stimulate the forming of flowers and fruit
 to speed up the cell division in Teacher of
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growing points
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9. 2. Cytokinin
- Cytokinin is produced by plants in the root
and then transported to the other organs
- The role of cytokinin are :
 influencing the growth of the root
 stimulating cell division
 retarding the aging of plant organs (leaf,
flower, and fruit)
 controlling the forming of flowers and fruit
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10. 3. Gibberellin
- Gibberellin is produced by the plants in the
root meristem tissue, stem meristem, and
young leaves
- The role of gibberellin are :
 stimulating the growth and development of
embryos and sprouts
 causing massive growth in plants
Producing big and seedless fruit
(parthenocarpy)
 stimulating the forming of flowers
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11. • External Factors
a. Water and Minerals
- water and minerals are absorbed from the soil
by the roots.
- the minerals required by plants are carbon,
oxygen, hydrogen, nitrogen, sulphur,
phosporus, calcium, potassium, and
magnesium. They are absorbed in form of ions
that dissolved in the water.
- water not only serves as a solvent but is also
required for photosynthesis
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12. b. Temperatures
- temperatures influences the work of enzymes
- a temperatures which is too low or too high will disrupt the work of
enzymes, so it will inhibit plant growth and development
- Every plant has the minimun, optimum, and maximum temperature to
grow
- the lowest temperature that still enables plants to grow and develop is
called the minimum temperature
- the most suitable temperature for plant growth and development is called
the optimum temperature
- the highest temperature that still enables the plants to grow and develop is
called the maximum temperature
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13. c. Humidity
- an environment with low humidity will
increase the evaporation (transpiration) of
plant so that the water and mineral
absorption from the soil will become more
frequent, this will increase the speed of
plant growth
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14. d. Light Intensity
- sunlight is highly required by plants for
photosynthesis, this process produces food that
is required for growth
- the light can also influence auxin hormone, it
will break down if it is exposed to sunlight
- for example, a sprout that is exposed to light
will slowly grow, while the sprout which put in a
dark place will grow faster
- the faster growth in darkness is called
etiolation
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15. c. GROWTH and DEVELOPMENT in
ANIMALS and HUMANS
• Growth and development in animals and humans occurs in all
parts of the body, different from those of plants which only
occur in certain parts.
• Growth and development in animals and humans begin at the
formation of the zygote
• One zygote will grow and develop until an embryo is formed
• In that particular stage, the embryo cells will differentiate to
form various tissues and develop into fetus
• The fetus will be born as a baby which then grow and develop
into a toddler, adolescent, and then a adult
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16. 2 phases in animals/humans’ growth
and development
• Embryonic phase
Is phase started with the establishing of
zygote up to embryo.
Fertilization is a process in which a fusion
of the sperm and ovum gamete occurs.
• Post-embryonic phase
Is phase after the embryo is formed. in
animals, post embryonic is only a change in
size, namely an increase in size of body parts.
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17. Factors that Affect Animals Growth
and Development
a. Genes
- a gene is a hereditary factor inherited by the parents
- genes will determine and control the basic patterns of
growth and development of an organism
b. Hormones
- hormones are secreted by endocrine glands
- the hormone which has the main role in human or animal
growth is the growth hormone (GH/Somatotropin)
- people who are lacking somatotropin will undergo stunted
growth, while those with an excessive amount of
somatotropin will undergo GIS A Biology Teacher of
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18. c. Food
- one of characteristics of living organism is the need for
food
- the most important roles of food is to construct the
body and as a source of energy.
- the food subtance which has the biggest role in growth
is protein
d. Water
- water is a solvent and a media for chemical reactions in
the body
- the chemical reactions will produce energy, help the
forming of new cells, and repair damaged body tissues
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19. e. Activity
- physical activity which is done for years will affect the
structures of bones and muscles
- for example, body builders or runners, they possess
good body posture and muscles.
- people who do less physical activity wil possess weaker
muscles and they will not properly develop.
f. Sunlight
- sunlight can alter provitamin D in the body into
vitamin D which is needed in the growth of bone
- lack of vitamin DCreated By Alfi Msk_ A Biology Teacher of can cause rickets
during childhood
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20. d. THE STAGE of HUMAN GROWTH
• Human growth and develoment begin from a very small ovum
cell
• The ovum is fertilized by sperm and the two nuclei will then
fuse to form a zygote
• A zygote will cleavage and become morulla
• A morulla is developed become blastula through blastulation
• A blastula is developed become gastrula through gastrulation
• A gastrula has 3 embrionic layer : ectoderm, mesoderm, and
endoderm
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21. • Ectoderm will diffrentiate become skin,
hair, nervous system, and sense organ
• Mesoderm will differentiate become
muscles, skeleton, reproductive organ,
transportation system, and excretion
system
• Endoderm will differentiate become
digestive system, and respiratory system
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22. Zygote Morula
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23. 1. Baby Birth
• After about 9 months of growing and developing inside the uterus, the
baby is ready to be born
• The baby, which has come out of the uterus is still connected to her
mother by umbilical cord and the placenta
• The umbilical cord and the placenta are then cut by the doctor or the
midwife
• At this stage, the physical connection between the mother and the
baby is broken, so that the baby can no longer obtain food and oxygen
from the mother
• When the umbilical cord and the placenta are cut, the breathing organs
will soon function, so that the baby can inhale the air, and usually it is
marked by the first cry
• The cry is also a sign that the baby is able to pump the respiratory air
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24. 2. THE TODDLER and CHILDREN
• The neonatal period is the first day of a
baby’s life until the age of four weeks
• In this period, the baby is able to adapt to life
outside the uterus, can start suckling at its
mother’s breast, and organs like lungs, heart,
and also excretion organs are already well
functioning
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25. 3. PUBERTY
• Puberty begins at about age 9 to 14, this
is the stage you are going through now
• Girls’ puberty characteristics are shown
in some physical changes ;
- the developing of hip and breasts
- the appearance of pubic hair
- the developing of reproductive organs,
is marked by the first menstruation
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26. • boys’ puberty characteristics are shown
in some physical changes ;
- the chest looks wider
- facial hair and pubic hair appears
- the voice change
- the deloping of reproductive organs, is
marked by the wet dream
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27. 4. ADULT STAGE
• In this stage, the growth of bones and
muscles begin to stop so adults cannot
grow taller
• Human psychological condition becomes
more stable than during adolescence
• People start to think about getting married
and producing offspring
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28. 5. OLD AGE
• The cell ability starts degenerating, this
causes some physical changes
• Like weaker bones, degenerating ability to
breath, degenerating elasticity of veins,
and also causes skin to wrinkle
• But sufficient nutrients and regular
exercise can inhibit aging
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29. e. METAGENESIS and
METAMORPHOSIS
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30. METAGENESIS
• Moss and ferns experience two
development stage in hteir life span, the
spore producing stage (sporophyte
generation, asexual) and the gamete
producing stage (gametophyte generation,
sexual)
• The alternation from sporophye to
gametophyte or vice-versa is called
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31. Moss Metagenesis
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32. Fern Metagenesis
Spore
Protalium
Anteridium Arkegonium
Spermatozoid Ovum
Zygote
Fern
Spore
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33. Metamorphosis
• Is the shape and structural alternation
which occurs in animals, starting from the
embryo stage to adult
• Animal which undergo metamorphosis
are insects and frogs
• Metamorphosis is differentiated into two
types ; the complete metamorphosis and
the incomplete metamorphosis
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34. Complete metamorphosis
• The metamorphosis which passes the
stages egg, larva, pupa, and adult (imago)
• In metamorphosis, the increase of body
size is a growth process, while the change
of the body shape from egg to adult is
development process
• For example, butterflies and frogs
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35. Frog
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39. Butterflies
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40. Flies
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41. Incomplete Metamorphosis
• Only passes the stages of egg, nymph
(young animal), and imago ( adult animal)
• No significant change of body shape
occurs
• For example, grasshoppers, cockroaches,
and crickets
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43. Grasshopper
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