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Science - Life Science

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Life science is concerned with the study of living organisms and their interactions with each other and their environments. Life science examines the structure, function, growth, origin, evolution, distribution, and classification of living things. Specialized disciplines of life sciences are grouped by the type of organism being studied: botany is the study of plants, zoology the study of animals, microbiology the study of microscopic organisms.

Life science instruction must include the inquiry knowledge and skills described in the inquiry section of the Science Core Curriculum. Instruction should be engaging and relevant and strong connections must be made to students' lives.

 

Kindergarten-Grade 2

Essential Concepts and/or Skills

Understand and apply knowledge of the characteristics of living things and how living things are both similar to and different from each other and from non-living things
Living things share some common characteristics that are both similar to and different from non-living things.

Different species of plants and animals have different observable characteristics by which they can be classified.

Understand and apply knowledge of life cycles of plants and animals
Plants and animals have life cycles that include being born, developing into adults, reproducing, and eventually dying.

Plants and animals closely resemble their parents.

Understand and apply knowledge of the basic needs of plants and animals and how they interact with each other and their physical environment
Organisms have basic needs. For example, animals need air, water, and food; plants require air, water, nutrients, and light.

Organisms interact with each other and their physical environment.

Organisms can survive only in environments in which their needs can be met. 

The world has many different environments, and distinct environments support the life of different types of organisms.

Understand and apply knowledge of ways to help take care of the environment
Chapter 12 of the Iowa Administrative Code states that science instruction shall include conservation of natural resources; and environmental awareness.

Humans depend on their natural and constructed environments.

Humans change environments in ways that can be either beneficial or detrimental to themselves or other organisms.

Understand and apply knowledge of basic human body structures (human body parts and their functions)
Humans have distinct body structures for functions including but not limited to thinking, walking, holding, seeing and talking.

Understand and apply knowledge of good health habits
See 21st Century Skills of the Iowa Core.

 

Grades 3-5

Essential Concepts and/or Skills

Understand and apply knowledge of organisms and their environments, including:

  • Structures, characteristics, and adaptations of organisms that allow them to function and survive within their habitats.
  • How individual organisms are influenced by internal and external factors.
  • The relationships among living and non-living factors in terrestrial and aquatic ecosystems.

Animals depend on plants. Some animals eat plants for food. Other animals eat animals that eat the plants.

An organism’s patterns of behavior are related to the nature of that organism’s environment, including the kinds and numbers of other organisms present, the availability of food and resources, and the physical characteristics of the environment. When the environment changes, some plants and animals survive and reproduce, others die or move to new locations.

All organisms cause changes in the environment in which they live. Some of these changes are detrimental to the organism or other organisms, whereas others are beneficial.

Understand and apply knowledge of environmental stewardship
Chapter 12 of the Iowa Administrative Code states that science instruction shall include conservation of natural resources; and environmental awareness.

Humans change environments in ways that can be either beneficial or detrimental to themselves or other organisms.

Understand and apply knowledge of basic human body systems and how they work together
The human organism has systems which interact with one another. These systems include circulatory, respiratory, digestive, musculoskeletal, etc.

Understand and apply knowledge of personal health and wellness issues
See 21st Century Skills of the Iowa Core.{/slide}

 

Grades 6-8

Essential Concepts and/or Skills

Understand and apply knowledge of the basic components and functions of cells, tissues, organs, and organ systems
Living systems at all levels of organization demonstrate the complementary nature of structure and function. Important levels of organization for structure and function include cells, organs, tissues, organ systems, whole organisms, and ecosystems.

All organisms are composed of cells. Most organisms are single cells; other organisms, including humans are multi-cellular.

Cells carry on the many functions needed to sustain life. They grow and divide, thereby producing more cells. This requires that they take in nutrients, which they use to provide energy for the work that cells do and to make the materials that a cell or an organism needs.

Specialized cells perform specialized functions in multi-cellular organisms. Groups of specialized cells cooperate to form a tissue, such as muscle. Different tissues are, in turn, grouped together to form larger functional units, called organs. Each type of cell, tissue, and organ has a distinct structure and set of functions that serve the organism as a whole.

Understand and apply knowledge of how different organisms pass on traits (heredity)
Every organism requires a set of instructions for specifying its traits. Heredity is the passage of these instructions from one generation to another.

Hereditary information is contained in genes, located in the chromosomes of each cell. Each gene carries a single unit of information. An inherited trait of an individual can be determined by one or by many genes, and a single gene can influence more than one trait. A human cell contains many thousands of different genes.

The characteristics of an organism can be described in terms of a combination of traits. Some traits are inherited and others result from interactions with the environment.

Understand and apply knowledge of the complementary nature of structure and function and the commonalities among organisms
Living systems at all levels of organization demonstrate the complementary nature of structure and function. Important levels of organization for structure and function include cells, organs, tissues, organ systems, whole organisms, and ecosystems.

Understand and apply knowledge of:

  • interdependency of organisms, changes in environmental conditions, and survival of individuals and species.
  • the cycling of matter and energy in ecosystems.

All organisms must be able to obtain and use resources, grow, reproduce, and maintain stable internal conditions while living in a constantly changing external environment.

Regulation of an organism’s internal environment involves sensing the internal environment and changing physiological activities to keep conditions within the range required to survive.

Behavior is one kind of response an organism can make to an internal or environmental stimulus. A behavioral response requires coordination and communication on many levels, including cells, organ systems, and whole organisms. Behavioral response is a set of actions determined in part by heredity and in part from experience.

Species acquire many of their unique characteristics through biological adaptation which involves the selection of naturally occurring variations in populations.

Biological adaptations include changes in structures, behaviors, or physiology that enhance survival and reproductive success in a particular environment.

For ecosystems, the major source of energy is sunlight. Energy entering ecosystems as sunlight is transferred by producers into chemical energy through photosynthesis. That energy then passes from organism to organism in food webs.

Understand and demonstrate knowledge of the social and personal implications of environmental issues
Chapter 12 of the Iowa Administrative Code states that science instruction shall include conservation of natural resources; and environmental awareness.

The number of organisms an ecosystem can support depends on the resources available and abiotic factors, such as quantity of light and water, range of temperatures, and soil composition. Given adequate biotic and abiotic resources and no disease or predators, populations (including humans) increase at rapid rates. Lack of resources and other factors, such as predation and climate, limit the growth of populations in specific niches in the ecosystem.

Understand and apply knowledge of the functions and interconnections of the major human body systems including the breakdown in structure or function that disease causes
The human organism has systems for digestion, respiration, reproduction, circulation, excretion, movement, control, and coordination, and for protection from disease. These systems interact with one another.

Disease is a breakdown in structures or functions of an organism. Some diseases are the result of intrinsic failures of the system. Others are the result of damage by infection by other organisms.

 

Grades 9-12

Essential Concepts and/or Skills

Understand and apply knowledge of the cell
Principles that underlie the concept and/or skill include but are not limited to:

Structures and functions

  • Cell structures underlie functions
  • Cell membranes; absorption and diffusion
  • Basic cell processes

Cells have particular structures that underlie their functions. Every cell is surrounded by a membrane that separates it from the outside world. Inside the cell is a concentrated mixture of thousands of different molecules which form a variety of specialized structures, notably the nucleus, mitochondria, ribosomes, chloroplasts, and the endoplasmic reticulum. Some cells have external structures facilitating movement (cilia and flagella).

Functions and chemical reactions

  • Enzymes catalyze reactions
  • Food molecules (macromolecules) break down to provide molecules for synthesis
  • Cell respiration breaks down complex molecules to provide energy

Most cell functions involve chemical reactions. Food molecules taken into cells react to provide the chemical constituents needed to synthesize other molecules. Both breakdown and synthesis are made possible by protein catalysts, called enzymes.

The chemical bonds of food molecules contain energy. Energy is released when the bonds of food molecules are broken and new compounds with lower energy bonds are formed. Cells temporarily store this energy in phosphate bonds of a small high-energy compound called ATP.

Note: Degree of depth for cell respiration is not intended to reach the level of glycolysis and Krebs cycle.

Cells grow and divide

  • Cells grow and divide in a cell cycle

Cell regulation allows cells to respond to their environment and to control and coordinate cell growth and division. Environmental factors can influence cell division.

Photosynthesis

  • Photosynthesis links sun energy to usable energy
  • Basic process of photosynthesis

Plant cells contain chloroplasts as sites of photosynthesis. Plants and many microorganisms use solar energy to combine molecules of carbon dioxide and water into complex, energy rich organic compounds and release oxygen to the environment.

Understand and apply knowledge of the molecular basis of heredity
Principles that underlie the concept and/or skill include but are not limited to:

  • Genetic information in cells
  • DNA structure specifies genetic information in genes
  • Genes direct and control protein synthesis
  • DNA mutations

In all organisms, the instructions for specifying the characteristics of the organism are carried in DNA, a large polymer formed from subunits of four kinds (A, G, C, and T). The chemical and structural properties of DNA explain how the genetic information that underlies heredity is both encoded in genes (as a string of molecular “letters”) and replicated (by a templating mechanism). DNA mutations occur spontaneously at low rates. Some of these changes make no difference to the organism, whereas others can change cells and organisms. Some mutations can be caused by environmental factors.

DNA, chromosomes, and sexual reproduction

  • DNA forms chromosomes.
  • Organisms have two copies of each chromosome.
  • Humans have 22 pairs plus two sex chromosomes.
  • Sex cells (sperm and egg) transmit genetic information through the processes of meiotic cell division and fertilization.

Each DNA molecule in a cell forms a single chromosome. Most of the cells in a human contain two copies of each of 22 different chromosomes plus two chromosomes that determine sex: a female contains two X chromosomes and a male contains one X and one Y. Transmission of genetic information to offspring occurs through meiosis that produces egg and sperm cells that contain only one representative from each chromosome pair. An egg and a sperm unite to form a new individual.

Note: Students should understand there are two versions of cell division; one maintains genetic continuity and one allows for genetic variability.

Basic Inheritance Patterns

  • Variability occurs as a result of fertilization
  • Basic patterns of inheritance can be identified

The fact that an organism is formed from cells that contain two copies of each chromosome, and therefore two copies of each gene, explains many features of heredity, such as how variations that are hidden in one generation can be expressed in the next. Different genes coding for the same feature code for it in different ways thus leading to identifiable patterns in heritable traits. These patterns of inheritance can be identified and predicted.

Understand and apply knowledge of biological evolution
Principles that underlie the concept and/or skill include but are not limited to:

Species evolution

  • Species evolve over time
  • Evolution is consequence of: Population potential, genetic variability, finite resources and environmental selection

Species evolve over time. Evolution is the consequence of the interactions of (1) the potential for a species to increase its numbers, (2) the genetic variability of offspring due to mutation and recombination of genes, (3) a finite supply of the resources required for life, and (4) the ensuing selection by the environment of those offspring better able to survive and leave offspring.

Natural Selection

  • Natural selection scientifically explains the fossil record
  • Natural selection explains molecular similarity of diverse species
  • Natural selection is a mechanism for evolution leading to organism diversity

Natural selection and its evolutionary consequences provide a scientific explanation for the fossil record of ancient life forms, as well as for the striking molecular similarities observed among the diverse species of living organisms. The great diversity of organisms is the result of more than 3.5 billion years of evolution that has filled every available niche with life forms.

Relations to common ancestor

  • Current diverse species are related by descent from common ancestors

The millions of different species of plants, animals, and microorganisms that live on earth today are related by descent from common ancestors.

Biological classification

  • Biological classification is based on evolutionary relationships
  • Species is the most fundamental classification unit

Biological classifications are based on how organisms are related. Organisms are classified into a hierarchy of groups and subgroups based on similarities in development and DNA sequences which reflect their evolutionary relationships. Species is the most fundamental unit of classification.

Note: this is not to be construed as a review of organisms included in classification categories such as kingdoms and phyla (e.g. is it not a review of all the invertebrates and vertebrates.) Diversity of this nature is included in the Middle School curriculum category "Knowledge of diversity and adaptations of organisms."

Understand and apply knowledge of the interdependence of organisms
Principles that underlie the concept and/or skill include but are not limited to:

Materials cycling

  • Atoms and molecules cycle (examples: carbon, nitrogen, oxygen cycles)

The atoms and molecules on the earth cycle among the living and nonliving components of the biosphere.

Energy flow

  • Energy transformation from producers through levels of consumer and decomposers

Energy flows through ecosystems in one direction, from photosynthetic organisms to herbivores to carnivores and decomposers. These tropic levels can be illustrated by food chains and food webs.

Organism interrelationships

  • Cooperation and competition within ecosystems
  • Interrelationships and interdependency lead to long term stable systems

Organisms both cooperate and compete in ecosystems. The interrelationships and interdependencies of these organisms may generate ecosystems that are stable for hundreds or thousands of years.

Humans modify ecosystems

  • Human modification of ecosystems
  • Habitat destruction threatens global stability

Human beings live within the world's ecosystems. Increasingly, humans modify ecosystems as a result of population growth, technology, and consumption. Human destruction of habitats through direct harvesting, pollution, atmospheric changes, and other factors is threatening current global stability, and if not addressed, ecosystems will be irreversibly affected.

Understand and apply knowledge of matter, energy, and organization in living systems
Principles that underlie the concept and/or skill include but are not limited to:

Sunlight energy conversion

  • Living systems require continuous energy input
  • Sunlight serves as the original energy source for life
  • Plants photosynthesize producing building blocks for making macromolecules and storing energy in chemical bonds
  • Cell respiration releases chemical bond energy stored during photosynthesis

Living systems require a continuous input of energy, derived primarily from the sun, to maintain their chemical and physical organization. Plants capture energy by absorbing light and using it to form strong (covalent) chemical bonds between the atoms of carbon containing (organic) molecules. These molecules can be used to assemble larger molecules (proteins, DNA, sugars, and fats). The chemical energy stored in bonds between the atoms can be used as sources of energy for life processes.

Note: the cellular mechanisms of photosynthesis and cell respiration are included in "The Cell"

Limiting factors

  • Ecosystem and population limiting factors
  • Ecosystems have finite resources
  • Environmental factors and finite resources influence ecosystem interactions

Living organisms have the capacity to produce populations of infinite size, but environments and resources are finite. The distribution and abundance of organisms and populations in ecosystems are limited by the availability of matter and energy and the ability of the ecosystem to recycle materials.

Matter and energy flow and conservation

  • Living systems require continuous energy input.
  • Matter and energy are conserved as they flow through and between organisms.
  • Some energy dissipates into the environment as heat.

All matter tends toward more disorganized states. Living systems require a continuous input of energy to maintain their chemical and physical organizations.

As matter and energy flows through different levels of organization of living systems--cells, organs, organisms, communities—and between living systems and the physical environment, chemical elements are recombined in different ways. Each recombination results in storage and dissipation of energy into the environment as heat. Matter and energy are conserved in each change.

Understand and apply knowledge of the behavior of organisms
Principles that underlie the concept and/or skill include but are not limited to:

Nervous systems and behavior

  • Nerve cell structure and function
  • Nerve cell communications through neurotransmitters
  • Sensor organs are specialized cells detecting environmental input

Multicellular animals have nervous systems that generate behavior. Nervous systems are formed from specialized cells that conduct signals rapidly through the long cell extensions that make up nerves. The nerve cells communicate with each other by secreting specific excitatory and inhibitory molecules. In sense organs, specialized cells detect light, sound, and specific chemicals and enable animals to monitor what is going on in the world around them.

The Human Organism – Basic Functions

  • The human immune system protects against microscopic and foreign substances entering the body and from cancer cells arising within.
  • The hormonal system exerts its influence by chemicals circulating in the blood.
  • Coordinated systems (nervous, muscular and bone) are necessary for locomotion.

Note: the broad topic of Human Biology is integrated into different areas of the middle school and high school curricula (see Middle School standard+ "Relationships between function and structure last two bullets). Thus some human body systems are omitted from this curriculum.

Printed from the Iowa Department of Education website on April 17, 2014 at 12:38am.