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1.1 The Characteristics of Life
Understand the basic characteristics of life.
The study of life is called biology.
Life on Earth is often functioning and behaving in strange ways.
When they reproduce, some species of puffballs are capable of producing trillions of spores.
Sand sharks kill and eat their siblings.
There is a small brain in the squid.
bristlecone pine trees outlive 10 generations of humans, while somebacteria live their entire life in 15 minutes.
The major groups of living organisms are shown in Figure 1.1.
Micro organisms with a very simple structure are widely distributed from left to right.
Protists are more complex thanbacteria.
The naked eye can easily see the other organisms in Figure 1.1.
They can be seen by how they get their food.
A morel digests its food outside.
An animal that eats its food is an aquatic animal, while a plant that makes its own food is a sunflower.
The study of life is called biology.
There are many different types of life on planet Earth.
Some of the basic characteristics of life are shared by all organisms.
Like non living things, organisms are composed of chemical elements.
The laws of chemistry and physics govern everything in the universe.
The characteristics of life give insight into the unique nature of life, and help to distinguish living organisms from non living things.
A cell is not made from living cells.
All life is connected by levels of biological organization.
The brain works with the spine and nerves to form the nervous system.
There are levels of biological organization beyond the individual organisms.
A group of organisms are capable of interbreeding.
A forest may have a population of gray squirrels and white oaks.
Animals and plants in the forest make up a community.
The basic characteristics of life cannot be carried out when cells are broken down into bits.
All levels of biological organization function as biological systems.
A change in carbon dioxide concentrations can affect the operation of organs, organisms, and entire ecosystems.
Life is connected at a variety of levels.
Without an outside source of energy and nutrition, living organisms can't maintain their organization.
Food can be used as building blocks or for energy.
Cells carry out a sequence of chemical reactions when they make their parts and products.
Chemical reactions occur in a cell.
Acquiring energy and nutrition.
The bear and fish need energy.
The sun is the most important source of energy on Earth.
Plants and other organisms can take solar energy and convert it into chemical energy through their photosynthesis process.
All life on Earth is metabolizing food.
This applies to plants.
The flow of energy and chemical between organisms is what defines how an ecology works.
Chemical cycling and energy flow begin when producers, such as grasses, take in solar energy and organic nutrition to produce food.
Chemical cycling occurs when chemicals move from one population to another in a food chain, until death and decomposition allow them to be returned to the producers.
Plants and other members of the food chain get energy from the sun as they feed on one another.
The energy is dissipated and returns to the atmosphere as heat.
Without solar energy and the ability of organisms to absorb it, the ecosystems wouldn't stay in existence.
Chemical cycling and energy flow begin when plants use solar energy to produce their own food.
In a food chain, chemicals and energy are passed from one population to another.
Chemicals are returned to living plants when organisms die.
When it comes to the climate of the environment, energy flow and nutrient cycling are the most important factors.
Deserts and forests require a lot of rain.
Tropical rain forests and coral reefs are where solar energy is most abundant.
The grasslands in North America are home to many animals, including rabbits, hawks, and various types of grasses.
Hawks feed on rabbits and other organisms, while rabbits feed on grasses.
Maintaining a state of biological balance is a must to survive.
In order for life to continue, temperature, humidity, acidity, and other factors must be within the tolerance range of the organisms.
Homeostasis is maintained by systems that monitor internal conditions.
Organisms have control mechanisms that do not require conscious activity.
The nervous system may be involved in controlling these mechanisms.
Your blood sugar levels are kept within normal limits when you are studying and don't eat lunch.
The behavior of organisms regulates their environment.
These behaviors are controlled by the nervous system in animals.
A lizard can raise its internal temperature by basking in the sun or by moving into the shade.
Living organisms interact with the environment.
Single-celled organisms can respond to their environment.
In some cases, the snapping of whiplike tails moves them away from light or chemicals.
More complex responses can be managed by multicellular organisms.
A vulture can detect a carcass a kilometer away.
A monarch butterfly can sense the approach of fall and begin its flight south.
Animals dart toward safety when the leaves of a land plant turn toward the sun.
Appropriate responses allow the organisms to carry on with their daily activities.
Organisms show a variety of behaviors as they compete for energy, shelter, and mates.
Complex communication, hunting, and defense behaviors are displayed by many organisms.
Life is what comes from life.
All forms of life are capable of making another one of their own.
The organisms split in two.
In most multicellular organisms, the reproductive process begins with the sperm and egg from one partner and the egg from the other partner.
The union of sperm and egg results in an immature stage, which progresses through stages of change to become an adult.
Random combinations of sperm and egg ensure that the offspring have different characteristics.
An embryo develops into a whale, a yellow daffodil, or a human because of its specific set of genes.
The genes are made of long molecule.
The instructions for the metabolism and organization of the particular organisms are provided by DNA.
All cells in a multicellular organisms have the same set of genes, but only certain genes are turned on in specialized cells.
There are obvious differences between species, and you may notice that not all members of a species are the same.
These differences are caused by changes in the genetic information.
There is a source of variation in the genetic information.
The observable differences in eye and hair color are examples of mutations.
Even within a group of organisms with the same genes, there is a staggering diversity of life.
Some organisms have characteristics that allow them to be more suited to their way of life.
Modifications that make organisms better able to function in a particular environment are called adaptation.
penguins are adapted to an aquatic existence A waterproof coat is formed by covering an extra layer of downy feathers with short, thick feathers.
Birds are kept warm in cold water by layers of blubber.
penguins have long, flattened wings that are suitable for swimming.
The flat feet allow them to walk on land, even though their feet and tails serve as rudders in the water.
The penguins use their bellies to slide across the snow in order to conserve energy.
The eggs are protected by a pouch of skin when they are carried on their feet.
The birds can huddle together for warmth while standing erect.
Living organisms can adapt.
The penguins have evolved complex behaviors to adapt to their environment.
Life on Earth is very diverse because organisms respond to changing environments by adapting.
The framework for evolutionary change is provided by Page 6 adaptation.
"An unrolling" is the way in which populations of organisms change over the course of many generations to become more suited to their environments.
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