Directions: Read the Passages and Answer the Questions to the Best of Your Ability. ALL

Name ______Date ______Block _____

Characteristics of Life

Directions: Read the passages and answer the questions to the best of your ability. ALL of the answers are in the reading. A good strategy when reading a passage is to read the questions first and highlight the answers as you read.

Most people feel confident that they could identify a living thing from a nonliving thing, but sometimes it’s not so easy. Scientists have argued for centuries over the basic characteristics that separate life from non-life. Some of these arguments are still unresolved. Despite these arguments, there does seem to be some generally accepted characteristics common to all living things. Anything that possesses all these characteristics of life is known as an organism.

1. The scientific term for a living thing is called an ______.

1. MADE UP OF CELLS

Scientists know that all living things are organized. The smallest unit of organization of a living thing is the cell. A cell is a collection of living matter enclosed by a barrier known as the plasma or cell membrane that separates it from its surroundings. Cells can perform all the functions we associate with life.

Cells are organized and contain specialized parts that perform particular functions. Cells are very different from each other. A single cell by itself can form an entire living organism. Organisms consisting of only a single cell are called unicellular. A bacterium or a protist, like amoebas and paramecia, are unicellular. However, most of the organisms you are familiar with, such as dogs and trees, are multicellular. Multicellular organisms contain hundreds, thousands, even trillions of cells or more. Multicellular organisms may have their cells organized into tissues, organs, and organ systems. Whether it is unicellular or multicellular, all structures and functions of an organism come together to form an orderly living system.

Functional cells are not found in nonliving matter. Structures that contain dead cells or pieces of cells are considered dead. For example, wood or cork cut from a tree is made up largely of cell walls. The cells are no longer functional.

1. All living things are made up of ______.
2. What is the simplest level at which life may exist?______
3. Are all cells alike? ______
4. All cells perform various jobs or ______.
5. What surrounds a cell and separates it from its environment? ______
6. What is the difference between unicellular and multicellular organisms?

1. Give an example of two multicellular organisms and two unicellular organisms.

1. Multicellular organisms can be organized into what other levels?

1. Examine these 2 organisms. Which one is unicellular and which is multicellular (label each)?

POND ORGANISM CRAB

(Under a microscope)

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2 & 3. REPRODUCTION and DNA (genetic material)

Perhaps the most obvious of all the characteristics of life is reproduction, the production of offspring. Organisms don’t live forever. For life to continue, organisms must replace themselves and pass on their genetic material. Reproduction is not essential for the survival of an individual organism, but is essential for the survival of a population. A species is a group of organisms that can breed and produce fertile offspring.A population is defined as a group of species that live in the same area. If individuals in a species never reproduce, it could mean an end to that species’ existence on Earth, also known as extinction.

There are two basic types of reproduction: sexual and asexual. The main goal of reproduction is for the organism to pass on its DNA, deoxyribonucleic acid, to the next generation. DNA is the genetic blueprint that makes organisms individually unique. In order for organisms to pass on their DNA they must reproduce either sexually or asexually. Sexual reproduction requires that two parent cells (sperm and egg= gametes) unite to produce a new, genetically different organism. Organisms reproducing sexually do not always have “sex.” In some cases, sperm and egg are released into the waterwhere they meet. This is also known as broadcast spawning. Some organisms that utilize the latter are fish, sponges, and corals. Most familiar organisms, such as maple trees, birds, bees, seals, deer, etc. reproduce sexually. In asexual reproduction a single organism can reproduce without the aid of another. Sometimes these organisms can just divide themselves in two through a process known as binary fission. Bacteria reproduces via binary fission. Other types of asexual reproduction include budding (sponges and hydra), fragmentation (sea stars), and parthenogenesis (snakes).

1. Define reproduction.

1. Must EVERY member of a particular species (one kind of organism) be able to reproduce in order for the species to survive? Explain why or why not.

1. What would happen if all individuals in a species were sterile (not able to have babies)?

1. Reproduction is NOT essential for the survival of an individual ______but is essential for the survival of the ______.
2. What is meant by extinction?

1. What is the main goal of reproduction?

1. What is DNA? Why is it important?

1. Name and define the two basic kinds of reproduction.

1. Highlight the organisms that reproduce asexually and circle the one that reproduces sexually.

BACTERIA HYDRASEA URCHIN

4. GROWTH AND DEVELOPMENT

Adults don’t always look like the babies of a species. All organisms begin their lives as single cells. Over time, these organisms grow and take on the characteristics of their species. Growth results in an increase in the amount of living material and the formation of new structures.

All organisms grow, and different parts of organisms may grow at different rates. Organisms made up of only one cell may change little during their lives, but they do grow. On the other hand, organisms made up of numerous cells go through many changes during their lifetimes. Think about some of the structural changes your body has already undergone in your short life. All of the changes that take place during the life of an organism are known as its development.

A snowball grows when you roll it over fresh snow! Why isn’t it a living thing? The growth of the snowball is not internal. It does not grow by producing more cells like organisms. It just adds on more material to the outside. Someone has to roll the snowball. It won’t grow bigger by just sitting there, and it certainly cannot change liquid water or solid ice into new snow from which it can grow larger. This is one of the differences between growth of a living thing and growth of a nonliving thing.

1. How do all organisms begin life?
2. What is the difference between growth and development?

1. Do unicellular organisms GROW? Do unicellular organisms DEVELOP?

1. Do multicellular organisms GROW? Do multicellular organisms DEVELOP?

1. Label the graphic which BEST shows growth and the one which BEST shows development.

______

5. OBTAIN AND USE ENERGY / METABOLISM

Energy is the ability to make things change. Energy is important because it powers life processes. It provides organisms with the ability to maintain balance, grow, reproduce, and carry out other life functions. Metabolism is the chemical process that breaks down or builds up materials taken in by organisms. Some organisms obtain energy from the foods they eat or, in the case of plants and several other types of organisms, the foods that they produce. Organisms that get energy from the food they eat are called heterotrophs, and they break that energy down through a process known as cellular respiration. Organisms that use energy from the sun to make their own food (which they then use for energy) are called autotrophs.The latter process is also known as photosynthesis. Organisms that live in areas where sunlight is lacking, such as the deep sea, are called chemoautotrophs, and they rely on chemicals from the deep sea vents to survive, a process known as chemosynthesis.

As you’ll learn, energy doesn’t just flow through individual organisms; it also flows through communities of organisms, or ecosystems, and determines how organisms interact with each other and the environment.

1. Define energy.

1. Why is energy important to a living organism?

1. Define metabolism.

1. What is the difference between an autotroph, heterotroph, and chemoautotroph?

1. What is the name of the process that plants use to make their own food using energy from the sun?

1. Identify each of the organisms below as either a heterotroph or an autotroph.

______

67. RESPOND TO THE ENVIRONMENT / STIMULUS and MAINTAINING HOMEOSTASIS

Living things live in constant connection with the environment, which include factors such air, water, weather, temperature, as well as plants and animals. The factors that can directly impact the survival of biotic factors (living things) are known as abiotic factors. Abiotic factors are described as nonliving things that have a huge impact on an organism’s survival rate, such as sunlight, nutrients, pH, temperature, and water. For example, if the seawater in the bay drastically turns cold, many of the fish will die because they cannot maintain proper body temperature. This intense and drastic temperature change will kill them, this is also known as a fish kill, and most deaths that result in this way are considered a natural process, much like red tide (harmful, toxic, algal bloom).

External environmental factors act as stimuli and can cause a response from living things. A stimulus is something that causes a physiological response. Organisms need to respond to the changes in order to stay alive and healthy. For example, if you go outside on a bright summer day, the sun may cause you to squint. Perhaps the bark of an approaching dog causes you to turn your head quickly. Just as you are constantly sensing and responding to changes in your environment so are all other organisms. For example, a specialized leaf on the Venusflytrap senses the light footsteps of a soon-to-be-digested green bottle fly. The plant responds to this environmental stimulus by quicklyclosing the leaf together.

An organism must respond to changes in its internal environment as well. Internal conditions include factors such as water, nutrients,body temperature, hormone levels, and minerals inside the body. Adjustments to internal changes help organisms maintain a stable internal environment. The regulation of an organism’s internal environment to maintain conditions suitable for life is called homeostasis. Or you can just think of it as keeping everything in BALANCE! For example, you have a “thermostat” in your brain that reacts whenever your body temperature varies slightly from 37°C (about 98.6°F). If this internal thermostat detects a slight rise in your body temperature on a hot day, your brain signals your skin to produce sweat. Sweating helps cool your body.

The ability of mammals and birds to regulate body temperature is just one example of homeostasis. Mechanisms of homeostasis enable organisms to regulate their internal environment, despite changes in their external environment.

1. What are some environmental factors (stimuli) that organisms respond to? List six.

1. Define abiotic and biotic factors.

1. What are two internal factors that organisms respond to?

1. Give two examples from the reading of how living things respond to changes in their environment.

1. If light is applied to a human eye, how does it respond?

1. Describe homeostasis.

8. EVOLUTION

When we think of the term evolution we often think of Charles Darwin and all of the discoveries he made around the Galapagos Islands. The theory of evolution has been built upon for decades; therefore, there is a wide range of scientific evidence that supports it.Evolution is considered a unifying topic of biology because it explores the diversity of organisms, as well as the similarities that unite them. Evolution is defined as a change in a species over time; process of biological change by which descendants come to differ from their ancestors (Holt McDougal Biology Text, 2012).

There are five main pieces of evidence scientists use to continue to build upon the theory of evolution: fossil record, embryology, biogeography, comparative anatomy, and molecular DNA evidence. The fossil record allows us to observe the remains of plants and animals that lived in the past and learn how they have changed from generation to generation. Fossils are formed in sedimentary rock layers called strata. The oldest are found in the deep rock layers, while the youngest or most recent organismsare found closer to the surface. Embryology is the study of embryos orthe larval stages of organisms. The individuals look very similar to each other early on, but are drastically different when they reach adulthood.It is believed that the similarity in embryos suggests that they all evolved from a distant common ancestor. Biogeography is the study of the distribution of organisms around the world. When Darwin explored the Galapagos Islands, he proposed that species of finches, a local bird, closely resembled the species that resided on the nearest mainland, and that somehow they migrated. Darwin knew that each island had different ecosystems with different abiotic and biotic factors. He believed, that over time, the traits became established on the islands mainly due to the fact that the mainland population was too far away and that their food sources differed. Therefore, the birds either had to adapt or they wouldn’t survive. Comparative anatomy is the study ofthe structures of living and fossilized animals, and looking at the similarities (homologies) that indicate evolutionarily close relationships. For example, a human hand, a bat wing, and a dolphin flipper represent homologous structures, meaning that they are all made up of the same structures, but function differently. The similarities suggest that all of the latter descended from a common ancestor. Lastly, DNA evidence is the most concrete piece of evidence because scientists are looking at the amino acid sequence of individual organisms, and we know that DNA is unique to each individual. Scientists tend to look at a protein called cytochrome c, located in the mitochondria of the cell. They look at cytochome c because most animals have this protein, making it easier to compare. In short, they simply look at the amino acid sequences and match them up. This is a very complicated process to understand and we will explore this in more detail later. Utilizing and studying the five pieces of evidence discussed above, allows scientists to understand how organisms descended with modification from a common ancestor.

Another way evolution happens is through natural selection via adaptation. Adaptation is defined as an inherited trait that gives an organism an advantage and is passed on to future generations. The inherited traits allow a species to survive in a specific environment, as well as successfully reproduce so that their genetic material is passed on to their offspring. If the trait has a low success rate, it will not be passed on, and will eventually die out. There are occasions when different populations of the same species live in different environments, therefore, they have different needs and adapt differently. For example, Darwin’s finches, they evolved from one species into 14 because they ate different types of food (seeds) on the different islands. This allowed speciation to occur, and they evolved into different species. Scientists observedspeciation by examining their beaks.

1. Define evolution.

1. List the five pieces of evidence that supports the theory of evolution.

1. Define adaptation.

1. How do adaptations increase a population’s survival or success?

1. How can species of the same population become different species?

9. CHEMICAL UNIQUENESS

Carbon based molecules, also known as macromolecules, are the foundation of life and make all living organisms chemically unique. The four groups of complex macromolecules: carbohydrates, lipids, proteins, and nucleic acids, make up all living systems. These macromolecules allow organisms to live and thrive in their environments.

They do all have one thing in common, and that is the universal element that is found in all of them, carbon. Carbons unique bonding properties allow it to form four covalent bonds at one time because it has four outer electrons in its outermost energy level. We will be exploring these amazing macromolecules throughout the year and discussing their importance in great detail.

1. What are the four macromolecules found in all living things?

1. Which element is considered the building block of life due to its unique bonding properties?

REVIEW! Let’s put it all together!

List the Characteristics of ALL LIVING THINGS

1. ______
2. ______
3. ______
4. ______
5. ______
6. ______
7. ______
8. ______
9. ______

Life is organized into many levels. The simplest level at which life exists is the cell. Life is also organized on nonliving levels (below the cell) and levels above the organism. Using your notes arrange the following levels of organization in order from simplest to most complex --- ecosystem, atom, population, organ, molecule, biome, tissue, cell, organ system, organism, community

LEVELS OF ORGANIZATION

NONLIVING

______

______

LIVING

____CELL______

______

______

______

___ORGANISM___

______

______

______

______

References

An introduction to evolution.(n.d.). Retrieved July 30, 2016, from

Characteristics of Life.(n.d.).Retrieved June/July, 2016.

Characteristics of Life.(n.d.). Retrieved July 30, 2016, from

Nowicki, S. (2012).Biology Holt McDougal. Houghton Mifflin Harcourt Publishing Company.

Final Assessment (HONORS)

Directions- Research one organism (your choice) and explain in detail, how your specific organism exhibits all of the characteristics needed to be considered a living organism. You must support each characteristic with examples and details.

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Modified by A. StahlPage 1