Unit C: Cycling of Matter in Living Systems

SCIENCE 10

Program of Studies

Unit C: Cycling of Matter in Living Systems (Nature of Science Emphasis)

Overview: The fundamental unit of life, the cell, is an example of an efficient open system comprised of a cell membrane and organelles that carry out the basic functions of all living organisms. Students will learn that technological advancements in microscopy have enhanced the study of cells and cellular processes. The understanding of life processes at the cellular level can also be applied to multicellular organisms.

Links to Science

The following science concepts are related to the content of Unit C.
  • life processes, and structure of plants - Grade 7 Science, Unit B: Plants for Food and Fibre
  • organisms, cells, system organs, tissues - Grade 8 Science, Unit B: Cells and Systems
Focusing Questions:
  • How did the cell theory replace the concept of “spontaneous generation” and revolutionize the study of life sciences?
  • How do single-celled organisms carry out life functions?
  • How do plants use specialized cells and processes to accomplish the same functions as a single cell, but on a larger scale?
  • How does imaging technology further our understanding of the structure and function of cells?

Key Concepts

The following concepts are developed in this unit and may also be addressed in other units at other grade/course levels. The intended level and scope of treatment is defined by the outcomes below.
  • microscopy and the emergence of cell theory
  • cellular structures and functions, and technological applications
  • active and passive transport of matter
  • relationship between cell size and shape, and surface area to volume ratio
  • use of explanatory and visual models in science
  • cell specialization in multicellular organisms; i.e., plants
  • mechanisms of transport, gas exchange, and environmental response in multicellular organisms; i.e., plants

Outcomes for Science, Technology and Society (STS) and Knowledge

Students will:
  1. Explain the relationship between developments in imaging technology and the current understanding of the cell
    • trace the development of the cell theory: all living things are made up of one or more cells and the materials produced by these, cells are functional units of life, and all cells come from pre-existing cells
      (e.g., from Aristotle to Hooke, Pasteur, Brown, and Schwann and Schleiden; recognize that there are sub-cellular particles, such as viruses and prions, which have some characteristics of living cells)
    • describe how advancements in knowledge of cell structure and function have been enhanced and are increasing as a direct result of developments in microscope technology and staining techniques
      (e.g., electron microscope, confocal laser scanning microscope [CLSM])
    • identify areas of cell research at the molecular level
      (e.g., DNA and gene mapping, transport across cell membranes)
  2. Describe the function of cell organelles and structures in a cell, in terms of life processes, and use models to explain these processes and their applications
    • compare passive transport of matter by diffusion and osmosis with active transport in terms of the particle model of matter, concentration gradients, equilibrium and protein carrier molecules
      (e.g., particle model of matter and fluid-mosaic model)
    • use models to explain and visualize complex processes like diffusion and osmosis, endo- and exocytosis, and the role of cell membrane in these processes
    • describe the cell as a functioning open system that acquires nutrients, excretes waste, and exchanges matter and energy
    • identify the structure and describe, in general terms, the function of the cell membrane, nucleus, lysosome, vacuole, mitochondrion, endoplasmic reticulum, Golgi apparatus, ribosomes, chloroplast and cell wall, where present, of plant and animal cells
    • compare the structure, chemical composition and function of plant and animal cells, and describe the complementary nature of the structure and function of plant and animal cells
    • describe the role of the cell membrane in maintaining equilibrium while exchanging matter
    • describe how knowledge about semi-permeable membranes, diffusion and osmosis is applied in various contexts
      (e.g., attachment of HIV drugs to cells and liposomes, diffusion of protein hormones into cells, staining of cells, desalination of sea water, peritoneal or mechanical dialysis, separation of bacteria from viruses, purification of water, cheese making, use of honey as an antibacterial agent and berries as a preservative agent by traditional First Nations communities)
    • describe cell size and shape as they relate to surface area to volume ratio, and explain how that ratio limits cell size
      (e.g., compare nerve cells and blood cells in animals, or plant root hair cells and chloroplast-containing cells on the surface of leaves)
  3. Analyze plants as an example of a multicellular organism with specialized structures at the cellular, tissue and system levels
    • explain why, when a single-celled organism or colony of single-celled organisms reaches a certain size, it requires a multicellular level of organization, and relate this to the specialization of cells, tissues and systems in plants
    • describe how the cells of the leaf system have a variety of specialized structures and functions; i.e., epidermis including guard cells, palisade tissue cells, spongy tissue cells, and phloem and xylem vascular tissue cells to support the process of photosynthesis
    • explain and investigate the transport system in plants; i.e., xylem and phloem tissues and the processes of transpiration, including the cohesion a nd adhesion properties of water, turgor pressure and osmosis; diffusion, active transport and root pressure in root hairs
    • explain and investigate the gas exchange system in plants; i.e., lenticels, guard cells, stomata and the process of diffusion
    • explain and investigate phototropism and gravitropism as examples of control systems in plants
    • trace the development of theories of phototropism and gravitropism
      (e.g., from Darwin and Boysen-Jensen to Went)

Skill Outcomes

(focus on scientific inquiry)
Initiating and Planning
Students will:
Ask questions about observed relationships, and plan investigations of questions, ideas, problems and issues
  • define and delimit problems to facilitate investigation
    (e.g., how do plants adjust to accommodate different environmental conditions such as varying levels of light and fertilizer)
  • design an experiment, identifying and controlling major variables
    (e.g., design an investigation to determine the effect of CO2(g) concentration on the number of chloroplasts found in an aquatic plant cell)
  • state a prediction and a hypothesis based on available evidence and background information
    (e.g., hypothesize how biochemical interconversions of starch and glucose might regulate the turgor pressure of cells; hypothesize the direction of root and plant growth of a bean plant growing on a rotating turntable, and predict the effects of varying RPMs on the angle of growth)
  • identify the theoretical basis of an investigation, and develop a prediction and a hypothesis that are consistent with the theoretical basis
    (e.g., use the particle theory to hypothesize how the rate of diffusion is affected by varying particle size, and then predict the rates of diffusion of a sucrose solution and a starch solution when placed into dialysis tubing in a beaker of water)
  • formulate operational definitions of major variables
    (e.g., define concentration gradient, equilibrium)

Performing and Recording
Students will:
Conduct investigations into relationships between and among observable variables, and use a broad range of tools and techniques to gather and record data and information
  • carry out procedures, controlling the major variables and adapting or extending procedures
    (e.g., perform an experiment to determine the effect of tonicity on plasmolysis and deplasmolysis in plant cells, such as staminal hairs or aquatic leaf cells, identify variables that do affect plasmolysis, such as the amount of light and heat, and control these variables)
  • use instruments effectively and accurately for collecting data
    (e.g., use a microscope to observe movement of water in plants; prepare wet mounts of tissue from flowering plants, and observe cellular structures specific to plant and animal cells; stain cells to make them visible)
  • estimate quantities
    (e.g., compare sizes of various types of cells under the microscope; calculate magnification, field of view and scale)
  • compile and organize data, using appropriate formats and data treatments to facilitate interpretation of the data
    (e.g., organize data obtained from measuring daily temperature and bloom dates of plant species, such as aspen, poplar, common purple lilac and crocus to determine a relationship between the two variables)
  • use library and electronic research tools to collect information on a given topic
    (e.g., upload and download text, image, audio and video files on emerging technologies for studying cells)
  • select and integrate information from various print and electronic sources or from several parts of the same source
    (e.g., create electronic documents containing multiple links, or summarize articles based on the scientific principles and/or technological developments)

Analyzing and Interpreting
Students will:
Analyze data and apply mathematical and conceptual models to develop and assess possible solutions
  • compile and display, by hand or computer, evidence and information in a variety of formats, including diagrams, flow charts, tables, graphs and scatterplots
    (e.g., collect data on the number of stomata per unit area on various plant leaves that grow in areas of differing humidity, and compile this data in a spreadsheet and graph it to determine whether there is a relationship between the variables)
  • interpret patterns and trends in data, and infer or calculate linear and nonlinear relationships among variables
    (e.g., compare the surface area to volume ratio of various cells, and relate the findings to the function of each cell; trace ingredients in modern medicines to their traditional counterparts)
  • state a conclusion based on experimental data, and explain how evidence gathered supports or refutes the initial hypothesis
    (e.g., observe and record macroscopic and microscopic changes in a growing plant for evidence of differentiation)
  • explain how data support or refute a hypothesis or prediction
  • construct and test a prototype of a device or system, and troubleshoot problems as they arise
    (e.g., create a model of a cell to illustrate a certain function, for example, use a balloon and tape to represent a guard cell)
  • identify new questions or problems that arise from what was learned
    (e.g., determine the purpose of cellular structures from observations of fresh and prepared materials, using dissecting and compound microscopes, or micrographs)

Communication and Teamwork
Students will:
Work as members of a team in addressing problems, and apply the skills and conventions of science in communicating information and ideas and in assessing results
  • communicate questions, ideas and intentions; and receive, interpret, understand, support and respond to the ideas of others
    (e.g., describe cytoplasmic streaming in a single-celled organism, and communicate an inference about similar movement in the cells of a multicellular organism)
  • select and use appropriate numeric, symbolic, graphical and linguistic modes of representation to communicate ideas, plans and results
    (e.g., draw analogies between division of labour in cells and in communities; record and explain the movement of water in plants)

Attitude Outcomes

Interest in Science
Students will be encouraged to:
Show interest in science-related questions and issues, and confidently pursue personal interests and career possibilities within science-related fields
(e.g., apply concepts learned in the classroom to everyday phenomena related to cells and multicellular organisms; investigate careers in fields, such as botany, forestry, horticulture, cytology, genetics and health care)

Mutual Respect
Students will be encouraged to:
Appreciate that scientific understanding evolves from the interaction of ideas involving people with different views and backgrounds
(e.g., value the roles and contributions of men and women from many cultures in using science and technology to further our understanding of the cell and of living systems, recognize and appreciate the contributions of the traditional knowledge of Aboriginal peoples to science and technology)

Scientific Inquiry
Students will be encouraged to:
Seek and apply evidence when evaluating alternative approaches to investigations, problems and issues
(e.g., recognize that traditional Aboriginal cultures employed the principles of scientific inquiry through observation and experimentation to solve a variety of unique challenges)

Collaboration
Students will be encouraged to:
Work collaboratively in planning and carrying out investigations, as well as in generating and evaluating ideas
(e.g., assume responsibility for their share of the work in preparing for investigations, gathering and recording data; consider alternative approaches suggested by group members)

Stewardship
Students will be encouraged to:
Demonstrate sensitivity and responsibility in pursuing a balance between the needs of humans and a sustainable environment
(e.g., show care and respect for all forms of life; evaluate the impact on the environment of personal choices, as well as the choices scientists make when carrying out an investigation)

Safety
Students will be encouraged to:
Show concern for safety in planning, carrying out and reviewing activities
(e.g., demonstrate concern for self and others in planning and carrying out experimental activities; select safe methods of collecting evidence and solving problems)

Links to Mathematics

The following mathematics outcomes are related to the content of Unit C but are not considered prerequisites.
  • Concept Mathematics Course, Strand and Specific Outcome
  • Data Analysis and Collection - Grade 9 Mathematics, Statistics and Probability (Data Analysis), Specific Outcome 3
  • Measurement and Unit Conversions - Mathematics 10C, Measurement,Specific Outcomes 1, 2 and 3; Mathematics 10-3, Measurement, Specific Outcome 1; Mathematics 20-3, Algebra, Specific Outcome 3; Mathematics 30-3, Measurement, Specific Outcome 1
  • Rate, Ratio and Proportion - Grade 8 Mathematics, Number, Specific Outcomes 4 and 5
  • Graph Analysis - Grade 9 Mathematics, Patterns and Relations (Patterns), Specific Outcome 2; Mathematics10C, Relations and Functions, Specific Outcomes 1 and 4; Mathematics 20-3, Statistics, Specific Outcome 1
  • Solving Equations - Mathematics 20-3, Algebra, Specific Outcome 1
  • Scale Diagrams - Grade 9 Mathematics, Shape and Space (Transformations), Specific Outcome 4; Mathematics 20-2, Measurement, Specific Outcomes 2 and 3; Mathematics 20-3, Geometry , Specific Outcome 2


Unit Focus Questions

  1. How did the cell theory replace the concept of “spontaneous generation” and revolutionize the study of life sciences?
  2. How do single-celled organisms carry out life functions?
  3. How do plants use specialized cells and processes to accomplish the same functions as a single cell, but on a larger scale?
  4. How does imaging technology further our understanding of the structure and function of cells?

Chapter C3.0 Plants are multicellular organisms with specialized structures

Key Concepts:

  • Use of explanatory and visual models in science.
  • Cell specialization in multicellular organisms; i.e. Plants
  • Mechanisms of transport, gas exchange, and enviromental response in multicellular organisms; i.e. plants.

Learning Outcomes:

  • Explain why, when a single-celled organism or colony of single-celled organisms reaches a certain size, it requires a multicellular level or organization, and relate this to the specialization of cells, tissues, and systems in plants.
  • Describe how the cells of the leaf system have a variety of specialized srtuctures and functions.
  • Explain and investigate the transport system in plants.
  • Explain and investigate phototropism and gravitropism as examples of control systems in plants.
  • Trace the development of theories of phototropism and gravitropism.


C3.1 Cells, Tissues, and Systems

Multicellular organism are larger than unicellular organisms because:

Plant Structure

Groups of cells form tissues.
Tissuses contributing to the same functions form organs.
Organs working together form systems.
Systems working together form organisms.

Plants have two systems:

Specialization in Plant Cells

Plant cells specialize and perform very different functions such as: Cells that are part of the root system produce root hairs Dermal cells of the shoot system produce cuticles

The lower epidermal of leaves develop guard cells, that form tiny pores called stomata for gas exchange. Cells in the xylem and vascular system conduct water throughout the plant.



.

3.2 The Leaf and Photosynthesis

The Particle Model of Matter

Chloroplast: responsible for photosynthesis, unique to plant cells.

Gas Production in Plants

Plants get energy by photosynthesis in the presence of light. However, during the night plants survive by cellular respiration, the same process that animals use.
Photosynthesis:    6 CO2 + 6 H2O → C6H12O6 + 6 O2
Cellular Respiration:     C6H12O6 + 6 O2 → 6 CO2 + 6 H2O
Fortunately, plants produce far more oxygen during the day then they use at night, so there is lots of extra oxygen for us to breath.
The reactants for photosynthesis are carbon dioxide and water. We will look at the systems responsible:


.

C3.3 The Leaf Tissues and Gas Exchange

We will look at two systems in the plant. Breathing in (CO2) and out (O2) of gases through the bottom of the leaves. Transpiration which transports water and dissolved minerals from the ground up to the leaves. Water comes from vascular bundles and the air comes from the stroma. Photosynthesis takes place in the mesophyll layers.
Vascular bundle

Sensitivity of Stomata

Ground Tissue

Mesophyll - specialized ground tissue inside a leaf, made up of thin-walled cells containing chloroplasts.
Palisade tissue cells - column-shaped mesophyll cells in a plant leaf; responsible for photosynthesis.
Spongy mesophyll tissue - layer of loosely-spaced mesophyll cells in a leaf; the increased distance between cells promotes diffusion.
Make a sketch Microscopic view of the paired guard cells and stoma on the leaf surface of spiderwort (Tradescantia). An opening or stoma develops between the inflated (turgid) guard cells due to a differential thickening of their walls. When the guard cells lose water pressure on a hot day, they deflate and push together, thus closing off the stoma and reducing water loss (transpiration) through the leaf.
Vascular tissue - transport tissue formed of cells joined into tubes that carry water and nutrients through the body of the plant. There are 2 different types of vascular tissue.
Xylem tissue - vascular tissue that conducts water and minerals from the roots to the leaves in plants.
Phloem tissue - vascular tissue that transports carbohydrates and water from the leaves to other parts of the plant.
Sieve tube cells - cylindrical cells lacking nuclei and with perforated sides and end walls that allow the movement of phloem in plants.
Companion cells - type of small phloem cells adjacent to sieve tube cells that appear to control sugar transport in the phloem.


.

C3.4 Transport in Plants

Cohesion - the attraction of molecules to the same type of molecule. Water surface tension is caused by cohesion
Adhesion - the attractions of molecules to other type of molecules.

Photosynthesis

Root pressure - upwards force exerted on water in the xylem in the roots of some plants. The root cells have a higher concentration than the surrounding dirt (hypotonic) which draws water into the roots (osmosis).
From Root to Leaf: Water Transport in Plants
Tension - a stress cause by the action of a pulling force.
Transpiration pull - the tension or pull on water molecules in the xylem due to evaporation of water through the stomata or lenticels in a plant.
From Source to Sink: Sugar Transport in Plants
Pressure-flow theory - explanation of plant nutrient transport from leaves to other parts of the plant, driven by the pressure build-up of hypertonic solution in leaf phloem.
Pressure differences - the difference in pressure in two areas that may cause movement of substances.


.

C3.5 Control Systems

Stimuli - a change in the environment that causes a reaction by the organism.
Phototropism - directional plant growth in response to light.
Gravitropism - directional plant growth response to gravity: may be positive or negative: also called geotropism
Control systems - systems within the plant that produce definite responses to specific stimuli.

Investigations of Phototropism

Area of elongation - an area of cells in the developing plant, facing away from the light source, that each elongate in a phototropic response to the light stimulus; the substance that initiates the phototropic response is auxin
Auxin - type of plant hormone that promotes cell growth or elongation.
Hormone - chemical compound that travels fro its production site in an organism to other sites where it produces an effect.