Characteristics of Life

Questions and Answers

What are the two broadest categories used in biology to group the world around us?

Living (biotic) and non-living (abiotic).

How does non-living differ from dead?

Non-living means something was NEVER alive, while dead refers to something that was once living but is no longer.

Why is it sometimes difficult to determine if something is living?

It can be challenging to decide whether an organism meets all criteria for life.

What does the term 'abiotic' refer to?

Abiotic refers to non-living components of the environment. Signup and view all the answers

Can something that is considered non-living ever be classified as living? Explain.

No, non-living things were NEVER alive. Signup and view all the answers

What does the acronym MRS GREN stand for in relation to life processes?

Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition. Signup and view all the answers

How do earthworms move through the soil?

Earthworms have two muscle layers that contract alternately to propel them forward. Signup and view all the answers

What waste products are produced during respiration in earthworms?

Carbon dioxide and water. Signup and view all the answers

What enables earthworms to detect changes in their environment?

Earthworms have light-sensitive cells and cells that respond to touch and chemicals in their skin. Signup and view all the answers

What is a unique feature of earthworm reproduction?

Earthworms are hermaphroditic, producing both sperm and eggs but requiring mating. Signup and view all the answers

How do earthworms excrete waste?

Earthworms excrete nitrogenous wastes through tubules that open to the surface of their segments. Signup and view all the answers

How can earthworms grow after losing parts of their body?

Some earthworms can regenerate small parts of their body that have been lost or injured. Signup and view all the answers

What type of energy do earthworms obtain from their food?

Earthworms obtain energy-rich molecules such as glucose from their food. Signup and view all the answers

What is the primary function of nutrients in living organisms?

To provide energy and molecules for growth. Signup and view all the answers

How do chlorophyll-containing plants obtain their nutrients?

They produce nutrients like glucose through photosynthesis. Signup and view all the answers

What types of food do earthworms rely on for nutrition?

Manure, compost, dead plant material, fungi, microorganisms, and decaying animals. Signup and view all the answers

Describe the process by which earthworms break down food.

Food is taken in through the mouth, passes through the digestive canal, and is broken down into simpler molecules. Signup and view all the answers

What is glucose, and why is it important for earthworms?

Glucose is a simple sugar that provides energy and is absorbed into the blood for cell function. Signup and view all the answers

What are the three main parts common to both plant and animal cells?

Cell membrane, cytoplasm, and nucleus. Signup and view all the answers

What additional structure do plant cells have that animal cells do not?

Cell wall. Signup and view all the answers

What is the function of the cell membrane?

It controls what enters and leaves the cell. Signup and view all the answers

What is the jelly-like substance within cells called?

Cytoplasm. Signup and view all the answers

What genetic material is contained within the nucleus of the cell?

DNA. Signup and view all the answers

What do chloroplasts do in plant cells?

They are involved in photosynthesis. Signup and view all the answers

What is an organelle?

A specialized structure within a cell that performs a specific role. Signup and view all the answers

How do the chromosomes appear when a cell is not dividing?

As long, thin, and tangled threads called the chromatin network. Signup and view all the answers

What is the role of the endoplasmic reticulum in a cell?

The endoplasmic reticulum is involved in protein and lipid production and forms channels for molecules to move within the cell. Signup and view all the answers

Describe the main function of mitochondria in a cell.

Mitochondria are the sites of cell respiration, converting energy in food into usable energy for the cell. Signup and view all the answers

What structures are typically found on the surface of the endoplasmic reticulum?

The surface of the endoplasmic reticulum may be covered with ribosomes. Signup and view all the answers

What are chromosomes and their significance in the cell?

Chromosomes are made of genes and contain hereditary information, passed from one generation of cells to the next. Signup and view all the answers

What is a key feature of the mitochondrial structure?

Mitochondria have a folded inner membrane known as cristae. Signup and view all the answers

How are the membranes of the mitochondrion structured?

Mitochondria have a smooth outer membrane and a folded inner membrane. Signup and view all the answers

What does the vacuole in a plant cell contain?

The vacuole contains cell sap, which is a solution of sugars and other substances dissolved in water. Signup and view all the answers

How do plant cells differ from animal cells in terms of vacuoles?

Plant cells often have large vacuoles, while most animal cells have small or no vacuoles. Signup and view all the answers

What are two unique structures found in plant cells that are not present in animal cells?

Plant cells have a cell wall and chloroplasts, which are not found in animal cells. Signup and view all the answers

What is the role of the vacuole in maintaining plant cell firmness?

The vacuole helps maintain firmness by storing cell sap, which creates turgor pressure within the cell. Signup and view all the answers

List two structures that are present in both plant and animal cells.

Both plant and animal cells contain mitochondria and a nucleus. Signup and view all the answers

What is the main function of chloroplasts in plant cells?

The main function of chloroplasts is to perform photosynthesis. Signup and view all the answers

Describe the structure of the cell wall compared to the cell membrane.

The cell wall is much thicker than the cell membrane, which is much thinner. Signup and view all the answers

What is stored as starch in chloroplasts?

Excess glucose produced during photosynthesis is stored as starch. Signup and view all the answers

What green pigment is found in chloroplasts, and what is its role?

The green pigment chlorophyll is found in chloroplasts and absorbs sunlight for photosynthesis. Signup and view all the answers

What role do ribosomes play within chloroplasts?

Ribosomes are involved in protein synthesis within chloroplasts. Signup and view all the answers

What is the stroma in chloroplasts?

The stroma is the fluid-filled space within chloroplasts containing enzymes and dissolved materials. Signup and view all the answers

What are thylakoids and their significance in chloroplasts?

Thylakoids are membranous sacs stacked to form grana, involved in light-dependent reactions. Signup and view all the answers

How does the structure of chloroplasts relate to its function?

Chloroplasts have a double membrane and thylakoids to optimize light absorption for photosynthesis. Signup and view all the answers

What is the primary role of a taxonomist?

A taxonomist names, describes, and classifies organisms. Signup and view all the answers

Who is considered the first taxonomist and what classification method did he use?

Aristotle is considered the first taxonomist and he classified organisms into plants and animals. Signup and view all the answers

What did John Ray contribute to the field of taxonomy?

John Ray was the first to use Latin for naming organisms. Signup and view all the answers

What is the modern naming system developed by Carolus Linnaeus called?

The modern naming system is known as binomial nomenclature. Signup and view all the answers

What are the two parts of a scientific name?

The two parts of a scientific name are the genus and species. Signup and view all the answers

Why is the International Code for Binomial Nomenclature important?

It sets rules for naming organisms to prevent duplicated names. Signup and view all the answers

What is a taxon?

A taxon is a category or group of organisms. Signup and view all the answers

Name a mnemonic that helps remember the hierarchy of classification groups.

One example is 'Kids prefer chocolate over fresh green salad.' Signup and view all the answers

What are the two parts of a scientific name?

Genus and species. Signup and view all the answers

How is the genus name formatted in a scientific name?

The genus name is written starting with a capital letter. Signup and view all the answers

What is the role of the International Code for Binomial Nomenclature (ICBN)?

It contains the rules for naming organisms. Signup and view all the answers

What is the correct way to write a scientific name in print?

It is written in italics. Signup and view all the answers

List the two most specific groups in the classification hierarchy.

Genus and species. Signup and view all the answers

What prevents the duplication of scientific names?

All names must be approved by International Naming Congresses. Signup and view all the answers

What mnemonic can help remember the order of classification groups?

Kids prefer chocolate over fresh green salad. Signup and view all the answers

What do the terms 'taxon' and 'taxa' refer to?

Taxon is a category for related organisms; taxa are the plural form. Signup and view all the answers

What are the main characteristics of prokaryotes?

Prokaryotes are unicellular, microscopic organisms without membrane-bound organelles and have a cell wall made of biological material. Signup and view all the answers

Which kingdom includes mainly small eukaryotes that live in aquatic environments?

The kingdom Protoctista includes mainly small eukaryotes that often live in aquatic environments. Signup and view all the answers

What is the genus of modern humans?

The genus of modern humans is Homo. Signup and view all the answers

How does classification in biology primarily operate?

Classification in biology is primarily based on evolutionary relationships between organisms. Signup and view all the answers

What distinguishes the kingdom Animalia from other kingdoms?

The kingdom Animalia is distinguished by multicellular organisms that are typically heterotrophic, breathing oxygen, and capable of movement. Signup and view all the answers

What is the order of classification from kingdom to species for the Grizzly Bear?

The order of classification is: KINGDOM Animalia, PHYLUM Chordata, CLASS Mammalia, ORDER Carnivora, FAMILY Ursidae, GENUS Ursus, SPECIES Ursus arctos. Signup and view all the answers

Study Notes

Characteristics of Life

Organisms are categorized into living (biotic) and non-living (abiotic).
Non-living entities were never alive, while dead refers to former living organisms.
All living organisms consist of cells and exhibit organized structures.

Life Processes in Earthworms

Seven essential life processes represented by the acronym MRS GREN: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition.

Movement

Earthworms use two muscle layers to propel themselves through soil.

Respiration

Earthworms break down glucose in cells to release energy, producing carbon dioxide and water as waste.

Sensitivity

Earthworms possess light-sensitive cells in their skin that detect environmental changes.

Growth

Earthworms hatch from eggs and can grow over a meter; some can regenerate lost body parts.

Reproduction

Earthworms are hermaphroditic, producing both sperm and eggs, requiring mating to exchange sperm. Fertilized eggs develop in a cocoon.

Excretion

Toxic nitrogenous wastes are excreted via tubules along their body segments.

Nutrition

Earthworms consume manure, compost, and decaying matter, digesting food to absorb nutrients.

Cell Structure

Cells are fundamental units of life visible through microscopes, consisting of a cell membrane, cytoplasm, and nucleus.
Plant cells additionally have a cell wall and may contain chloroplasts for photosynthesis.

Organelles

Specialized structures within cells include mitochondria, endoplasmic reticulum, and Golgi bodies.
The nucleus contains DNA, which holds genetic information.

Cell Membrane and Cytoplasm

The cell membrane is selectively permeable, regulating substance entry and exit.
Cytoplasm is where metabolic reactions occur.

Mitochondria

Sites of cell respiration, converting food energy into a usable form.

Chloroplasts

Contain chlorophyll for photosynthesis, converting sunlight into chemical energy stored as glucose or starch.

Plant Cells vs. Animal Cells

Plant cells have distinct features: cell wall, large vacuole, and chloroplasts, while animal cells are generally smaller with no cell wall.

Taxonomist Role

Taxonomists classify organisms based on morphological, behavioral, genetic, and biochemical characteristics.

Historical Figures in Taxonomy

Aristotle: Classified organisms into plants and animals based on habitat.
John Ray: First botanist to use Latin for naming species.
Carolus Linnaeus: Developed binomial nomenclature, classifying organisms by structure, known as the "Father of Taxonomy".

Binomial Nomenclature

Scientific names consist of genus (capitalized) and species (lowercase), e.g., Panthera pardus.
Important for consistency across languages; names are italicized in print.

Rules for Naming Organisms

Governed by the International Code for Binomial Nomenclature to prevent name duplication.

Classification System

Taxa hierarchy: Kingdom, Phylum, Class, Order, Family, Genus, Species, remembered using mnemonics.

The Five Kingdoms

Prokaryotae: Unicellular organisms without membrane-bound organelles (e.g., bacteria).
Protoctista: Small eukaryotes, often aquatic, including algae and protozoa.

Taxons and Similarity

Classification is based on evolutionary relationships, with genera containing closely related species.

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Description

Distinguish between living and non-living things in biology, understanding the differences between non-living and dead organisms.