Reproduction

The ability to reproduce is a

very important property of life.

Living things that cannot

reproduce will slowly

disappear from the life map

and become extinct. Several

factors can prevent living

things from being a successful

breeder; however, this will not

be covered at this time.

Reproduction takes place at all

levels of the organization

when a single cell can reproduce a multicellular organism

also can reproduce. The cells result of reproduction usually

resembles its parent if not identical in some cases.

The mechanism of reproduction can be one of several

mechanisms:

Living things can reproduce sexually; this means male

and female organisms to produce sperm and egg, after

the sperm fertilizes the egg a new organism has been

reproduced.

Different organisms reproduce via asexual reproduction;

this does not require sperm and egg or fertilization at

the correct conditions a new organism will bud out from

the parent such as the Hydra.

The third mechanism can be seen in bacteria when one

cell is duplicated into two daughter cells.

For any of these mechanisms and any living organism's

condition, the environment must be good for reproduction

for the offspring to survive.

Growth & Development

Growth means an increase in the size and the number of

cells, the human body starts after fertilization as one cell

that undergoes mitosis and continues to increase in

numbers. After birth this continues and results in building

different organs and structures developed to reach their

functional level, DNA controls the degree and level of

growth and development.

The stages of development are also different from one

species to another in some animals they can reach the fully

developed organism in weeks or months for others will

require years. Any delays in the growth will result in delays

in development, which can be very harmful to the organism.

Movement

Movement is another property of living things, this

movement can result from the movement at the cell level in

which the cell will move substances and material across the

plasma membrane in and out, the next level can be

detected at the organ level the heart pushes blood out, the

small intestate continues to move digested materials and

skeletal muscles move the hall body as one unit. These

movements come via precise control and coordination.

Life on Earth

Life on earth is composed of

many different structures. The

goal of science is to explain

and identify all the

components. Biology is the

branch of science that aims to

explain life by identifying all

living things, differentiates

between them, recognize their

interactions with each other's

and with their environments.

Biology recognizes certain

properties of life. These properties distinguish living from

non-living; only living things have these properties and they

include:

organization

metabolism

responsive

reproduction

movements

growth and development

adapting

Organization

The pattern of organization is very important for all living

things to maintain their life. The organization is seen in all

life forms whether the organism is composed of trillions of

cells or it is just a single cell organism. The level of

organization is essential for functions because any changes

in the structure will result in a loss of the function.

Looking at the lowest level of an organization starts with

elements in which different atoms such as carbon,

hydrogen, and oxygen start to organize into molecules such

as water, proteins, carbohydrates, and lipids, the building

process continues when those molecules get organized into

defined structures known as organelles each of them will

have a unique structure and specialized functions.

Organelles make up the next level as they become

organized into one unit called the cell. The cell represents

the basic unit of life as they may exit alone and have all the

properties of life, but they start to group and specialized

into four major tissues, the epithelium, connective, muscular

and nervous tissue. When tissues are organized and

attached according to genetically preset codes and ratios

that result in what is known as an organ, different organs

will be built each with a unique function such as the heart,

stomach, and lung, which then organized into a system

where each system is composed of several organs all of

their function complies as one unit, and finally, several

systems such as the respiratory, digestive, nervous and

lymphatic systems make up one organism.

The organization does not stop at organism, it continues

when a group of organism lived together and depends in

each other forming what known as a population, several

populations usually lived closed and interact with other

creating one community. All the communities in one

geographical area as they interact with non-living things

such as water and mountains will establish a higher level of

an organization called an ecosystem.

Energy and Life

Energy is defined as the ability

to do work; all living things

require some level of energy

to keep them alive. The source

of energy is from the sun as

we are part of the solar

system. Living things have

different abilities in using this

energy in what is known as

metabolism activity. This

represents a sum of all

chemical reactions that take

place in living organisms and

result in the energy process. This energy can be used for all

different activities including growth, movements, and

respiration.

Metabolism is composed of catabolic and anabolic reactions.

Catabolic means the breakdown of macromolecules into

basic building blocks. Anabolic means using the materials

that resulted from the breakdown to rebuild the new

structures.

Living things are divided regarding metabolism into different

categories:

1. Autotroph – represents those organisms that can

produce their own food, because; they have the ability

to perform photosynthesis capturing the sunlight and

converted into stored chemical energy in food.

2. Heterotroph – organisms that can't make photosynthesis

and depend on produced foods.

3. Decomposers – the last group that is responsible to

recycle all the materials.

The energy level is conserved between these three levels of

living organisms.

Homeostasis

Homeostasis is a very

important concept of life, this

means staying within a level

of constant (staying the

same). Living things are part

of the ecosystem and that

means they have some kind of

interactions and changes, they

will never stay exact at all

times. This mechanism allows

them to adjust and come back

to the previous point. The

changes represent internal

and external causes that if not correct will cause harm to

the organs.

Homeostasis is a mechanism that has several components

to be functional.

First, it required a cause which is called a stimulation such

as a temperature or level of glucose in the blood, this has to

be detected by receptors and reported to a control center in

the nervous system where the information will be processed

and a design will be established and the order is carried to

target or effectors how will respond and make the

adjustments such as sweating.

Let us look at the example of temperature. If you stand

outdoors and the weather temperature is 105, heat will start

to go into your body if this continues your internal

temperature will be equal to the environment, this does not

happen because receptors in your skin detect this and

report to the hypothalamus, the hypothalamus sends orders

to targets, as a result, you will notice increase heart rate,

increase respiration, increase urination, and sweating this

will keep your body temperature the same. This is known as

the negative feedback loop, homeostasis also uses a

positive feedback loop in some conditions such as childbirth.

Adaptation

Since living things are part of an

ecosystem and all the things that

construct it, they are affected by

everything in that system. Weather and

other living organisms could affect living

things.

Successful organisms will manage to

make the required changes and

modifications that allow them to meet the current

conditions. The changes are triggered by modification in the

genetic inheritance to survive. If we look at the organism

that adapted to the condition we will find some differences

from the original population, and the one the adopted would

be the fit.

Reviewing the literature, we have many theories that try to

explain adaption and the way organisms evolve. The natural

selection theory provides some explanations, other theories

use fossils, comparative anatomy, and finally DNA studies to

trace and recognize evolutions.

Biodiversity

When we survey living things we find a massive number of

different things, they have so many similarities and some

differences among them. Scientists were looking for a

system that will allow them to group and classify all those

living things and avoid confusion and conflicts among living

things. Taxonomy was the science that solves this problem.

Taxonomy recognized and identified living things and placed

them in groups from the most to the least level. At each

level, the groups have similarities among them. This was

very useful because of the great number of different

species.

Taxonomy starts by identifying the Domains as the most

inclusive level. Three domains were identified and they are:

1. Bacteria: contain microscopic unicellular prokaryotes

2. Archaea: bacteria that look like unicellular bacteria

3. Eukaryote: includes most of the known living organisms

in which they are further organized into kingdoms.

Five kingdoms are recognized as the Monera, Protista, Fungi,

Plantae, and Animalia. Each kingdom is then grouped into

different phylum's and each of them is broken into several

classes. Each class contains different orders and each order

has several families, and family into genus and finally each

genus have several species.

The Scientific Method

The processes of science

come via a mechanism that

builds knowledge utilizing the

scientific method. This

mechanism starts from just an

observation and leads to a

theory or a law.

Observation is the first step

when a researcher noticed a

condition that he cannot

explain or understand. This

will trigger the process in which he will start to investigate

the conditions. The investigation starts reviewing the

previous data and literature to see if this observation was

addressed earlier in the literature and will help him in the

formulation of his research questions or what is known as

the hypothesis.

After proposing the research questions the research will

design an experiment to test the questions. At the end of

the experiment the data and results will be collected and

references about the questions, which lead him to reject,

some hypothesizes and accept the others.

The final stage would be to conclude the observation, this

conclusion will explain them, and several conclusions

usually will create a theory. When the theories reach more

acceptance via more scientific evidence then it will be

known as a law.

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