growth patterns a) sigmoid growth curve ( organism and population ) b) human growth curve c) limited...

GROWTH PATTERNS

a) sigmoid growth curve ( organism and population )b) human growth curvec) limited growth curve ( annual plants ) and unlimited

growth curve ( perennial plants )d) isometric growth ( fish ) and allometric growth

( human organs )e) intermittent growth curve ( arthropods )

By the end of the lesson the students should be able to:

give the types of growth curves describe the types of growth curvesgive the example of organisms which growth pattern follow the growth curves

122.3 Types of Growth Curves

Objectives

• Organism that have a sigmoid growth curve are:-–Individual organism / large size of

multi cell plants / animals

–Microorganisms population ( yeast, bacteria )

2Growth patternsSigmoid Growth Curves

3Growth patternsSigmoid Growth Curves

1Growth PatternsThe Patterns

• patterns of growth vary from species to species

• the patterns of growth in living multicellular organisms are:

allometric vs. isometric

limited vs. unlimited

human growth curve

Intermittent growth curve

human growth curve

• In human, the growth curve after birth appears to consist of two sigmoid curves, with two main rapid growth phases, the infant phase and the adolescent phase.

• A slower growth phase is known as the childhood phase can be found in between these two rapid growth phases.

2Growth patternsHuman Growth Curves


A BC D

infant phase adolescent phasechildhood phase

• Human growth curve:

i. Prenatal growth ( before birth )

ii. Postnatal growth ( after birth )



Prenatal growth Postnatal growth

• In embryos, the brain and the head will both start growth and development together in the early phase of life, while;


Prenatal growth


• The complete development of hands and feet only occurs in the later phase.

Prenatal growth


Postnatal growth

• Very rapid growth rate • Irrespective in both male

or female babies.

8Growth patternsHuman Growth Curves1. Infant phase:

• growth rate is slower.

• beginning at the age of four,

• the rate is slightly higher in boys than in girls

9Growth patternsHuman Growth Curves2. Childhood phase :

• growth rate is rapid.

• in the earlier part of this growth phase, females demonstrate a more rapid growth rate

• i.e. two years earlier than begins in males.


3. Adolescent phase:


3. Adolescent phase:

• At the later part of this growth phase, the male growth rate becomes higher than the female growth rate.

• This difference results in the females attaining puberty at an earlier age compared to males.

• Females attain puberty around the age of 12, while males attain puberty when they are about 14 years old.

• growth rate is zero • most individuals would have attained

maturity. • Males achieve this phase at the age

about 18 while females at the age around 16.

12Growth patternsHuman Growth Curves4. Adult phase:

• growth rate is negative• i.e. the body proportion will start to

decrease starting from the age of 30.

13Growth patternsHuman Growth Curves5. Ageing phase

• The growth of an organism to a maximum fixed size, which depends on the type of the organism.– Relative short life

span

14Growth patternsLimited Growth Curves


• A single Sigmoid growth shape

• Growth is complete when the organism achieves its maximum size. – and then

demonstrates the negative growth, senescence

• e.g. most plants and animals, including human



Annual plant growth curve eg: Pisum sativum ( Pea plant )

• In annual plants, the sigmoid growth curve of dry mass versus time shows a small reduction in dry mass in the initial part of growth, due to seed germination.

• During germination, food stored in the cotyledons is usually used up before the first leaves undergo photosynthesis.


• This loss of mass is later replaced when the first leaves develop and start photosynthesis.

• Later, growth rate is very rapid, until it becomes constant at a later stage.

• This rapid growth rate is maintained until the plant achieves maturity, after which the rate gradually reduces until it becomes zero.

• e.g: pea plant


• Refer to non-stop growth over a relatively long life span

• Example organisms demonstrate unlimited growth:

• Obelia colonies, • coral reefs and • multiple season woody

trees

19Growth patternsUnlimited Growth Curves

• The growth curve for unlimited growth comprises a series of small sigmoid curves.


• This type of curve shows that there is an increase in the mass and size every season.

• In plants that demonstrate unlimited growth, there is no fixed rate and the growth continues until enemies, natural catastrophe or diseases cause destructive effects on them.



Unlimited growth curve ( perennial plants )

23Growth PatternsAllometric Growth

The growth of an organism within which different organs grow at different rates from each other and from the overall growth.

• involves the change in size and external shape/ features of the organism

Allo= Gk. different


• involves the change in size and external

shape/ features of the organism

Allo= Gk. different

24

It shows the correlation between the growth and development of the organism

• e.g. in mammals: the growth rates of the lymphatic and reproductive tissues is different

• i.e. the growth rates of both tissues are the highest at the different stages of development

Growth PatternsAllometric Growth

25

• the mammalian lymphatic tissues grows rapidly during the early childhood years

• but during adolescence its growth rate is lower, why?

• the mammalian reproductive tissues grows faster during the stage of adolescence, why?

Growth PatternsAllometric Growth

This is because lymphoid tissues are required by a young individual to give it natural immunity and defense againts disease.This function is less needed during the adult phase.

The reproductive system only starts to grow and develop during the adolescent phase.

Similarly, in embryos, the brain and the head will both start growth and development together in the early phase of life, while the complete development of hands and feet only occurs in the later phase.

ALLOMETRIC GROWTH


29Growth PatternsIsometric Growth

The growth of an organism within the organs grow at the same rates with the other parts of the body.

• the relative size of the organs is constant• i.e. the size of the organs increase, but the

external features remain the same

• e.g. fish, grasshoppers, cockroaches

30Growth PatternsIsometric Growth

• not accompanied by a change in shape of the organism

31

e.g. in grasshoppers

Growth PatternsIsometric Growth

• the relative proportion of the organs and whole body (size and shape remain the same

32

e.g. in a cucumber leaf

Growth PatternsIsometric Growth

• It is a discontinuous growth occurs in insects & other

arthropods metamorphosis.

• Growth is limited by the hard exoskeleton during certain periods until the ecdysis / moulting process takes place.

• Then, growth occurs very suddenly at a rapid pace.(rate of movement)

• Produces a step-like (intermittant) growth curve.

• Each stage in between ecdysis is known as instar.

Growth PatternsIntermittent Growth Curve 33

in arthropods e.g. insects

5th instar

Ecdysis @

3rd instar

adult


Ecdysis

Ecdysis:

• also known as moulting

• a process of changing the old exoskeleton of arthropods replaced with new soft layer and later becomes harden again.

• occur periodically to allow growth and development.

• during ecdysis, arthropod breathes in a lot of air

- body expands and break the old exoskeleton


1. when old exoskeleton is removed,

2. arthropod once again breathing in more air to

increase it size before

3. newly formed layer of chitinious exoskeleton

hardens.

Ecdysis:


3722.5 Ecdysis and Metamorphosis

Ecdysis

• a process of changing in shape which occur from one stage to the following stage in animals (insect).

• two types: complete and incomplete

complete metamorphosis occur in holometabolic insects e.g. housefly, butterfly incomplete metamorphosis occur in hemimetabolic insects e.g. cockroach grasshopper

Metamorphosis: Definition


Complete Metamorphosis

larva

39

Incomplete Metamorphosis41

growth patterns a) sigmoid growth curve ( organism and population ) b) human growth curve c) limited...

Documents

patterns patterns of

human growth curve slide

slower growth phase

rapid growth rate

female growth rate

sigmoid growth curve

main rapid growth phases

sigmoid curves