Six Weeks In-service Course Pn Murniza Muhamad

Six Weeks In-Service Course Pn Murniza Muhamad

GIGANTISM

The creosote bush is native to arid regions of the southwestern United States and South America. These plants exhibit an interesting type of growth in which the crown of an individual plant splits into large lobes, each of which then bends back into the soil and develops its own roots and branches. One particular cluster in the Mojave Desert is estimated to be approximately 11,700 years old.

LIFE CYCLE OF FERN

skills • Explain the meaning of growth • Describe the pattern of growth by showing the changes in quantity, shape, size and rate of growth

Definition Growth is the permanent and irreversible increase in the parameter quantity (length, height, mass, surface area, volume and size)

Three phases of growth: – Cell division – Cell enlargement / expansion / assimilation – Cell differentiation

GROWTH • The Pattern of growth for plants and animals as shown by sigmoid curve The sigmoid curve is the S-shaped curve that has intrigued people throughout history. The curve sums up the story and time line of life itself; we start slowly, we experiment and falter, we then grow rapidly, then wax, and wane. It is the product life cycle, it is the biological life cycle. It describes the rise and fall of empires, dynasties, companies, and individuals. It also describes the course of love and relationships.

• Cells division or mitosis - the basis of growth - gave the living world an opportunity to increase the size of the organisms. • Cell enlargement / expansion Plants - cell grow by add some organic material to their cytoplasm, or - addition of water, into the large central vacuole, accounts for 90% of plant cell’s expansion Animals - cells grow by synthesizing a proteinrich cytoplasm, a metabolically expensive process • Involved assimilation

• Assimilation - taking substances from the environment and synthesis new molecules to increase the existence molecules (body cell). - total cytoplasm increased • Cytoplasm increased referred as increased the number of organelles in the cell like mitochondria, ribosome and etc.

• Cell differentiation – The process of specialization of cells with the same set of genetic information to produce a diversity of cell types – Differentiation reflects the synthesis of

different proteins in different types of cells.

Measuring Growth • Growth involves the increasing of protoplasm of an organism. • Growth can be estimated by measuring a particular parameter over a period of time. • The best parameter and commonly used to measure growth are:Length » Height » Mass » Surface Area »

Estimate length / height • Periodic linear measurement Eg: Measuring height for human being – the best way to measure the growth of an individual • Plant: height is not a suitable parameter to measure the growth because height of a tree does not give much information about the growth of branches, leaves, root and the food storage structures underneath the ground.

• The parameter chosen should be appropriate to the organism whose growth is to be measured. • In certain experiment, the best parameter that suitable to be used in determining growth are fresh mass and dry mass.

Fresh mass • Method : the mass without internal water removed • Advantages : – Easy and convenient – No need to kill the organism so its growth can be measured repeatedly • Disadvantage: – inaccurate and unbalanced measurement • fluctuation or varying water volume in the live organism (water ~ 70-90% wet mass) – Shows greater variation due to the environment or the organism behavior

Dry mass • Method : – Mass of organism after removing all the water from its body (drying process) – Kill the specimen – Dry in the oven (~110 °C) – Cool the sample in the dryer, repeatedly measured the weight and cool until get a constant weight – dry mass value Advantages : – Accurate measurement of the amount of organ matter present

Disadvantage: - Organisms are killed so growth of the same specimen cannot be repeatedly measure - Large samples of genetically identical organism need to be grown under similar conditions. - Time consuming

Isometric and allometric growth

Isometric (isos, same; metron, measure)

• growth occurs when an organ grows at the same mean rate as the rest of the body. •change in size of the organism is not accompanied by a change in shape of the organism. •The relative proportion of the organs and whole body remain the same. • eg: fish and certain insects.

Allometric ( allos, other; metron, measure) •growth occurs when an organ grows at a different rate from the rest of the body. •a change in size of the organism is accompanied by a change in shape of the organism.

•This pattern of growth is characteristic of mammals and illustrates the relationship between growth and development. •In almost all animals the last organs to develop & differentiate are reproductive organs. •can be observed only in those organisms with external genital organs.

• Allometric growth in humans. Note the changes in the proportion of body parts from 2 months to 25 years.

GROWTH IN HUMAN • The growth patterns show a smooth & gradual sigmoid-shaped curve. • In human, for example, there are two phases of rapid growth; one during the early years of life (infant), the other during adolescence. • Between these two phases there is a period of relatively slow growth (childhood).

»Human growth curve

• Human growth curve: i. Prenatal growth (before birth) ii. Postnatal growth (after birth) • The sequential major growth phases of a human:a. Infant phase: ~ Growth rate is very rapid & is irrespective of whether the baby is male or female

b. Childhood phase: ~ Growth rate is slower. ~ from the age of 4, it is slightly higher in males babies when compared to females. c. Adolescent phase: ~ Growth rate is rapid. ~start at the age of 12 years, females have a more rapid growth rate and later male growth rate becomes higher than the female growth rate

d. Adult phase: ~Growth rate is zero & most individuals would have attained maturity. ~ males – 18 years old, while female – 16 years old e. Ageing phase: ~ Growth rate is negative ~ size will start to decrease starting from the age of about 30 years.

male

GROWTH IN PLANTS

Below the point of the fleshy cotyledons is is the hypocotyls and above it is the epicotyl. •

• At the tip of the epicotyl is the plumule, consisting of the shoot tip with a pair of miniature leaves.

• The hypocotyls terminates in the radicle, or embryonic root. • The embryo of a grass seed is enclosed by two sheath, a coleorhiza, which covers the young root and a coleoptile, which cover the young shoot.

Seed Germination • In a seed, the embryo with its food supply is encased within a sometimes rigid, relatively impermeable seed coat that may need to be abraded before germination can occur. • Weather and passage through an animal’s digestive tract may be necessary for germination to begin.

• When temperature, light and water conditions are appropriate, germination can begin. In some cases, a period of chilling is required prior to germination. • This adaptation protects seeds from germinating until after the cold season. • At germination, the mobilization of the food reserves is critical. Hormones control this process.

Fig. 7.3.2(a). Seed germination

LETS DO AN ACTIVITY! Germinate some seeds and record observations on the growth of seedings