Biology

PATTERNS IN NATURE – Summary Notes

1. ORGANISMS ARE MADE OF CELLS THAT HAVE SIMILAR STRUCTURAL CHARACTERISTICS

1.1 Outline the historical development of the cell theory, in particular, the contributions of Robert Hooke and Robert Brown

The Cell Theory states that:
All living things are made of cells (Theodor Schwann & Matthias Schleiden)
Cells are the basic structural and functional unit of organisms (Theodor Schwann)
All cells come from pre-existing cells (Rudolf Virchow)

The historical development of the cell theory:
1485 – Leonardo Da Vinci used glass lenses to study small objects
1600 – the first compound microscope was made by Hans and Zacharias Janssen
1665 – Robert Hooke observed cork cells using a compound microscope and described ‘cells distinct from one another’
1676 – Anton von Leeuwenhoek described unicellular organisms in pond water
1831 – Robert Brown – observed the nucleus in plant and animal cells
1839 – Schleiden and Schwann formulated the cell theory that all living things are made up of cells. Schwann was the first scientist to see yeast cells producing new cells
1858 – Virchow stated that where a cell exists, there must be pre-existing cells
1880 – Walter Flemming described cell division from observations on living and stained cells

1.2 Describe evidence to support the cell theory
The evidence supporting the cell theory accumulated over a period of 600 years as the technology developed. The use of microscopic lenses to study living matter eventually provided enough data to establish the cell theory.
Little boxes distinct from one another (‘cells’) seen by Robert Hooke in 1665
Living microorganisms in pond water seen under the microscope (1676)
It was suggested that all organisms are made of cells (1824)
The nucleus in plant cells described by Robert Brown (1827)
More evidence accumulated for the idea that all organisms are made of cells. This included seeing yeast cells budding and producing new cells. From then the cell was regarded as the building blocks of life (1838)
In the twentieth century the Cell Theory was supported by the identification of call structures and their functions and the discovery of cellular mechanisms and processes.

1.3 Discuss the significance of technological advances to developments in the cell theory
Improvements in the microscope have enabled us to see the cell better and learn more about and develop the cell theory
For example the development of the light microscope enabled Hooke to see that living things were made up of cells
Biological stains used to view cells dividing, verifying the way cells reproduced

1.4 Identify cell organelles seen with current light and electron microscopes
LIGHT MICROSCOPE
ELECTRON MICROSCOPE
Nucleus
Mitochondria
Chloroplast
Endoplasmic Reticulum
Vacuole
Ribosomes
Cell wall/ membrane
Lysosomes

1.5 Describe the relationship between the structure of cell organelles and their function
ORGANELLE
FUNCTION
Cell
the basic unit of all living things, mage up of protoplasm (cytoplasm and a nucleus) surrounded by a cell membrane and, in plants and some organisms, a cell wall
Cell membrane the boundary surrounding the cell that controls what enters and leaves the cell.
Cell wall
(not present in animal cells) gives the cell strength and a strong structure. It is made of layers of cellulose fibers interspersed with other carbohydrates.
Centriole
an organelle present in animal cells, responsible for forming fibers called the spindle during cell division
Chlorophyll
green pigment found in all green plant cells, responsible for light capture in photosynthesis
Chloroplasts
organelles found in plant cells containing chlorophyll. Chloroplasts make glucose for the plant through photosynthesis
Endoplasmic Reticulum a system of parallel membranes running through the cell the transports material through the cell. The rough endoplasmic reticulum is covered with ribosomes that create proteins
Golgi Body apparatus for packaging proteins for transport out of the cell
Lysosome
a particle in the cytoplasm of cells containing a number of digestive enzymes capable of breaking down most of the constituents of living matter
Mitochondria
an organelle in all eukaryotic cells, responsible for cellular respiration and supplies the cell with ATP energy. It is made of two membranes in which some of the enzymes for respiration are embedded.
Nuclear membrane the thin skin around the nucleus with nuclear pores

Nucleolus a dark staining round body inside the nucleus of a cell, responsible for the formation of ribosomes
Nucleus
contains genetic material that controls all of the cells activities and is bounded by a membrane containing pores which allows RNA messengers to be sent around the cell.
Vacuole
filled with water cell sap. It forces the cell contents up against the cell wall making the cell rigid.

1.6 Use available evidence to assess the impact of technology, including the developments of the cell theory

1.7 Perform a first hand investigation to gather first hand information using a light microscope to observe cells in plants and animals to identify nucleus, cytoplasm, cell wall, chloroplast and vacuoles

1.8 Process information from secondary sources to analyse electron micrographs of cells and identify mitochondria, chloroplasts, Golgi bodies, lysosomes, endoplasmic reticulum, ribosomes, nucleus, nucleolus and cell membranes

2. MEMBRANES AROUND CELLS PROVIDE SEPARATION FROM AND LINKS WITH THE EXTERNAL ENVIRONMENT

2.1 Identify the major groups of substances found in living cells and their uses in cell activities

Organic Molecules:

CHEMICAL
FUNCTION
STRUCTURE
Lipids
Stores energy
Aids with vitamin absorption
Good insulation
Forms the structural part of all membranes in cells
Macromolecules that contain many carbon and hydrogen atoms, and a few oxygen atoms
Carbohydrates
Fuel source for metabolism
Provides energy for the body
Made of C,O,H (ratio of one oxygen for every two hydrogen atoms) Can be monosaccharaides, disaccharides or polysaccharides.
Saccharide = sugar
Proteins
Basis structure in cells
Forms part of tissues such as bone, hair and nails
With lipids they regulate the passage of substances across the cell membrane

Large complex macromolecules. Made of the long chains of amino acids each chain is called elements carbon, hydrogen, oxygen and nitrogen
Nucleic Acid
Contains an organisms genetic material, which codes for amino acids which make proteins
Includes DNA and RNA, are made from nucleotides (monomers). Each nucleotide has a 5-carbon sugar, a phosphate group, and a nitrogenous base.

Inorganic Molecules:

Chemical
Function
Structure
Iron
Helps attached hemoglobin to red blood cells to transport oxygen around the body
Fe 2+
Calcium
Allows for strong bones and teeth
Ca 2+
Water
A solvent. Most things are water soluble this allows water to transport them throughout the body. It is necessary for temperature regulation
2 hydrogen atoms 1 oxygen atom - liquid form
Polar molecule - one half is positive and other negative
Potassium
It is essential for maintaining proper fluid balance, nerve impulse function,
K +

2.2 Identify that there is movement of molecules into and out of cells
Substances required for cells to function move into the cell and waste substances need to move out of a cell. These substances enter and exit through the cell membrane.

2.3 Describe the current model of membrane structure and explain how it accounts for the movement of some substances into and out of cells
Cell membranes are selectively permeable because they allow only certain molecules to pass through them. The permeability of a membrane to a molecule depends on the molecules size or electrical charge (ions).

2.4 Compare the processes of diffusion and osmosis
Diffusion is the movement of molecules from a region of high concentration to a region of low concentration equilibrium is reached. This process does not require an energy input.

Osmosis is a specific type of diffusion; it is the movement of water molecules from a region of high concentration to a region of low concentration through a selectively permeable membrane.

2.5 Explain how the surface area to volume ratio affects the rate of movement of substances into and out of cells
The smaller the cell the larger the surface area to volume ratio. This is important because all substances must pass through the cell membrane. The greater the surface area the greater the rate of absorption. (e.g. if an organism is small, its survival rate would be higher because it is able to take in nutrients and remove waste more efficiently and this ensure growth and survival).

2.6 Plan, choose equipment or resources and perform a first hand investigation to gather information and use available evidence to identify the following substances in tissues
Glucose – add blue’s Benedicts to substance and place in water bath. Substance turns orange

Starch – using iodine. If starch is present substance turns dark purple.

Lipids – rubbing substance on brown paper. The paper becomes transparent.

Proteins – add biuret solution to substance. The substance turns into a mauve colour.

Chloride ions – add silver nitrate to substance. There should be a cloudy precipitate.

Lignin – place in phloroglucin solution and then into hydrochloric acid. Turns into a maroon colour.

2.7 Perform a first hand investigation to model the selectively permeable nature of a cell membrane

2.8 Perform a first hand investigation to demonstrate the difference between osmosis and diffusion
Cucumber experiment(osmosis) and potassium permanganate(diffusion)

2.9 Perform a first hand investigation to demonstrate the effect of surface area to volume ratio on rate of diffusion
Agar experiment

3. PLANTS AND ANIMALS HAVE SPECIALISED STRUCTURES TO OBTAIN NUTRIENTS FROM THEIR ENVIRONMENT

3.1 Identify some examples that demonstrate the structural and functional relationships between cells, tissues, organs and organ systems in multicellular organisms
Examples:
Muscle  Muscle Tissue  Heart  Circulatory System  Human
Chloroplasts  Palisade Cells  Palisade Tissue  Leaf  Photosynthetic system  Plant
3.2 Distinguish between autotrophs and heterotrophs in terms of nutrient requirements
Autotroph – an organism that can produce its own organic molecules from non-living sources (its nutrient requirements include carbon dioxide, water and macronutrients)

Heterotrophs – an organism that cannot produce its own organic molecules from living sources and therefore depends on other organisms to supply its nutritional needs (nutrient requirements include carbohydrates, proteins, lipids, vitamins and minerals)

3.3 Identify the materials required for photosynthesis and its role in ecosystems

Materials required for photosynthesis:
Carbon dioxide
Water
Chlorophyll
Sunlight
Enzymes

These materials are needed for the chemical process of photosynthesis to occur. The water and carbon dioxide provide he basic chemical building blocks for photosynthesis. Sunlight is then converted from radiant energy to chemical energy and reacts with chlorophyll, which is another essential component.

The importance of photosynthesis to the ecosystem:
All living things depend on photosynthesis as it converts radiant energy to sunlight energy
All living organisms either directly or indirectly eat plants (producers)
It converts carbon dioxide into oxygen for aerobic respiration
Organic compounds (proteins, lipids, carbohydrates) rely on photosynthesis for their production.

3.4 Identify the general word equation for photosynthesis and outline this as a summary of a chain of biochemical reactions Sunlight
Carbon Dioxide + Water Oxygen + Glucose + Energy Chlorophyll

Photosynthesis is a series of chemical reactions
Radiant energy from the sun is captured by chlorophyll in the thylakoids of the chloroplasts.
The light phase: involved the splitting of water using the energy of light
The light independent phase involves using the carbon to make sugar

3.5 Explain the relationship between the organization of the structures used to obtain water and minerals in a range of plants and the need to increase the surface area available for absorption
Roots absorb water and inorganic materials, they have root hairs in order to increase their surface area and absorb water and nutrients at a higher rate.
The uptake of water and mineral salts increase, due to root hairs, extensive branching of root systems and the entering of water through the epidermal cells across the entire surface of the root system.
Water: roots absorb water through osmosis, this is because the water in the soil has a higher concentration that within the cells of the plant. The water moves across the root to the xylem. The xylem transports the water and dissolved minerals upwards from the roots to the rest of the plant by transpiration

3.6 Explain the relationship between the shape of leaves, the distribution of tissues in them and their role
Leaves are structurally adapted to enable them to effectively function. They are made up of a number of different tissue, arranged in an organized way to maximize their efficiency in carrying out their functions. The structural features needed by a leaf for efficient photosynthesis are:
A large surface area, with an outer layer able to absorb light and carbon dioxide
Pores in the leaf surface or the exchange of gases with the environment
Cells inside that contain chloroplasts to trap the energy of sunlight
A water transport system from the root to the leaves
A food transport system from the leaves to other parts of the plant

The palisade cells and spongy cells make up the mesophyll, the layer between the leaf responsible for most of the plant’s photosynthesis.
Palisade cells are elongate cells that contain numerous chloroplasts and they are the main photosynthetic cells in leaves. They are situated immediately below the upper epidermis.
Spongy cells are the second most important photosynthetic cells. They have fewer chloroplasts that palisade cells and are irregular in shape and have large intercellular air spaces. Their main functions are gaseous exchange (the exchange of oxygen and carbon dioxide with the external environment in plants and animals.

3.7 Describe the role of teeth in increasing the surface area of complex foods for exposure to digestive chemicals
Teeth increase the surface area of food by breaking it into smaller pieces. This increases the rate of digestion of foods by enzymes.

The digestion of food involves:
Mechanical or physical breakdown, where food is chewed and chunks are physically broken down into smaller bits.
Chemical breakdown, where digestive enzymes act on the food to chemically break down the large complex into simpler, smaller molecules.

3.8 Explain the relationship between the length and overall complexity of digestive systems of a vertebrate herbivore and a vertebrate carnivore with respect to:
The chemical composition of their diet
The function of the structures involved

3.9 Plan, choose equipment or resources and perform first hand investigations to gather information and use available evidence to demonstrate the need for chlorophyll and light in photosynthesis
Covering the leaf with tape.

3.10 Perform a first hand investigation to demonstrate the relationship between surface area and rate of reaction
Agar jelly experiment

3.11 Identify data sources, gather, process, analyse and present information from secondary sources and use available evidence to compare the digestive systems of mammals, including a grazing herbivore, carnivore and a predominantly nectar feeding animal

4. GASEOUS EXCHANGE AND TRANSPORT SYSTEMS TRANSFER CHEMICALS THROUGH THE INTERNAL AND BETWEEN THE EXTERNAL ENVIRONMENTS OF PLANTS AND ANIMALS

4.1 Compare the roles of respiratory, circulatory and excretory systems
4.2 Identify and compare the gaseous exchange surfaces in an insect, a fish, a frog and a mammal
4.3 Explain the relationship between the requirements of cells and the need for transport systems in multicellular organisms

4.4 Outline the transport system in plants, including:
Root hair cells
Xylem
Phloem
Stomates and lenticels
Transport System
Description
Root
Allows the plant to have a strong structure
Gaseous exchange between roots and soil through the roots and root hairs
Stem
Support the leaves so they can access light
Transports of water and minerals to the leaves by the xylem
Transports the products of photosynthesis to the roots by the phloem
Xylem
A specialized tissue for the transport of water and dissolved inorganic materials from the roots to the leaves (only moves upwards)
Phloem
The vascular tissue in plants that transport organic nutrients from where they are manufactured, up and down the plant
Stomates

A pore located in the epidermis of leaves and stems through which gases such as water vapour, oxygen and carbon dioxide can enter and leave
Lenticels
Pores through which gaseous exchange occurs in the woody parts of plants.
The diffusion of oxygen, carbon dioxide and water vapour takes place through the lenticels

4.5 Compare open and closed circulatory systems using one vertebrate and one invertebrate as examples

4.6 Use available evidence to perform a first hand investigation and gather first hand data to identify and describe factors that affect the rate of transpiration
Filter paper in different environment.
The highest transpiration will occur on the days that are windy, hot, dry and sunny.
The lowest transpiration days will occur when the weather is humid, cold, wet and cloudy.

4.7 Perform a first hand investigation of the movement of materials in xylem or phloem
The movement of water through the xylem and phloem of celery (experiment)

4.8 Use available evidence to discuss, using examples, the role of technologies, such as the use of radioisotopes in tracing the path of elements through living plants and animals

5. MAINTENANCE OF ORGANISMS REQUIRES GROWTH AND REPAIR

5.1 Identify mitosis as a process of nuclear division and explain its role
Mitosis is an important process that involves the division of the cell nucleus. Its role is to pass the nuclear information of a cells’ to the daughter cells. Human cells have 46 chromosomes and every daughter cell produced also has 46 chromosomes. Mitosis is need for growth and repair.

5.2 Identify the sites of mitosis in plants, insects and mammals
Mitosis in mammals occur in the:
Skin
Hair/fur
Blood cells
Internal system

Mitosis in plants occur in the:
Macrosmatic tissue apical meristem in the tips and roots of the stem the vascular cambium area of roots and stem

Mitosis in insects occur in the: imaginal discs where massive an=mounts of mitosis occurs so that the adult form can arise from the pupal form areas of the body that need repair

5.3 Explain the need for cytokinesis in cell division
Cytokinesis is the final step in cell division. It is the division of the cytoplasm and is important to separate the newly formed daughter nuclei (to ensure each cell only has one nucleus). The outcome at the end of mitosis and cytokinesis is two daughter cells that are identical to the parent cell.

5.4 Identify that nuclei, mitochondria and chloroplasts contain DNA
During the process of cytokinesis, the organelles such as mitochondria and chloroplasts are distributed evenly to the daughter cells,. It is necessary for the organelles in the cytoplasm to replicate so that they are not reduced in quantity. Mitochondria and chloroplasts contain their own small amounts of DNA, so that they are able to replicate.

5.5 Perform a first hand investigation using a microscope to gather information from prepared slides to describe the sequence of changes in the nucleus of plant or animal cells undergoing mitosis
Onion cells at different stages of mitosis (experiment)