Biology Notes

MRS C GREN

• Seven life processes:

  • Movement

  • Reproduction

  • Sensitivity

  • Control

  • Growth

  • Respiration

  • Excretion

  • Nutrition

Definitions of Life Processes

• Movement: Not staying in the same position.

• Reproduction: Producing offspring.

• Respiration: Releasing energy from food.

• Sensitivity: Ability to recognize and respond to changes in the environment.

• Control: Maintaining a constant internal environment (e.g., blood glucose levels, body temperature).

• Growth: Increasing in size and mass.

• Excretion: Removal of toxic waste products (organs of excretion include kidneys, skin, and lungs).

• Nutrition: Either making their own food (plants by photosynthesis) or eating organisms.

MRS C GREN Circuit Activity

• Go around the room to different stations and tick the processes that are visible.

Life Processes - Plenary

• Complete a crossword in teams.

  • Across:

    • 6: How organisms get energy from food (Respiration).

    • 8: Process rids the organism of toxic waste products (Excretion).

    • 9: Reproduction results in the creation of this (Offspring).

  • Down:

    • 1: An example of one of the things that a human needs to control (Temperature).

    • 2: These are an example of a non-living creature that may cause disease (Viruses).

    • 3: An increase in size and mass (Growth).

    • 4: If something does all the 8 MRS C GREN processes we know it is _? (Living).

    • 5: Animals use muscles to do this (Movement).

    • 7: The process by which plants make their own food (Photosynthesis).

Levels of Organisation

• Levels of Organisation (in order of size):

  • Cells

  • Tissues

  • Organs

  • Organ systems

• Unicellular: Being built of one cell.

• Multicellular: Being built of many cells.

• Example: Cardiac muscle cell → Heart muscle (tissue) → The heart (organ) → The circulatory system (organ system).

• Learning objective: To describe the levels of organisation within organisms: organelles, cells, tissues, organs, and systems.

Lego Building Blocks

• Lego represents how complex structures are built from smaller units, analogous to biological organization.

Completing Sentences

• Cells with similar function are grouped together as tissues.

• Tissues with different functions are grouped together to carry out a particular function known as an organ.

• In animals and plants, jobs are usually carried out by several organs working together as part of an organ system.

Categorizing Tissues, Organs, and Organ Systems:

• Tissues: Blood, Bone, Epithelial, Glandular, Muscle, Nervous, Skeletal, Vascular bundles.

• Organs: Brain, Heart, Kidney, Lung, Skin, Leaves, Roots.
  *Organ systems: Digestive

Organ Systems in Humans

• Various systems exist, including:

  • Respiratory

  • Digestive

  • Circulatory

  • Excretory

  • Reproductive

Organ Systems in Plants

• Xylem vessels: Carry water.

• Phloem vessels: Carry water.

• Vascular bundles: Transport system from root to leaves.

• Palisade mesophyll cells: Carry out photosynthesis.

• Epidermal tissue: Covers the plant for protection.

Systems in the Human Body

• Complete a table showing the organs in each organ system and their main functions.

• The respiratory system allows oxygen to enter the blood and carbon dioxide to be excreted.

• The digestive system breaks down food and absorbs products into the blood.

• The circulatory system transports substances (e.g., blood with oxygen) around the body.

• The excretory system forms and stores urine for the removal of toxic waste products from metabolism.

• The reproductive system produces sperm (male) and eggs (female) to produce offspring.

Plenary

• Teams answer questions related to the levels of organization.

Animal vs. Plant Cells

Animals

• Multicellular

• No cell walls

• Move (using nervous system)

• Store carbohydrate in cells as glycogen

• Eat food for nutrition

Plants

• Multicellular

• Chloroplasts in cells

• Make food via photosynthesis

• Cell wall (cellulose)

• Store starch in cells

• Sucrose stored in fruits sometimes

Components of Cells

• Animal Cell:

  • Cell membrane

  • Cytoplasm

  • Nucleus

  • Mitochondria

• Plant Cell:

  • Cell membrane

  • Cytoplasm

  • Nucleus

  • Mitochondria

  • Chloroplast

  • Cell Wall

  • Vacuole

Functions of Cell Components

• Cytoplasm: Jelly-like substance where chemical reactions take place.

• Nucleus: Controls activities of cell and contains the genetic material (DNA in the form of chromosomes).

• Cell surface membrane: Selectively permeable barrier that controls which substances enter and leave the cell.

• Mitochondria: Carry out reactions of respiration for the release of energy.

• Cell wall: Layer of cellulose that helps support the cell and strengthens it.

• Vacuole: Filled with cell sap – a reservoir for water and chemicals.

• Chloroplasts: Filled with green pigment chlorophyll for photosynthesis.

Microscopes

• Viewing Animal and Plant Cells

  • Draw animal and plant cells viewed under the microscopes and calculate the magnification $M = I/A$ where:
    $M$ is the magnification
    $I$ is the size of the image
    $A$ is the actual size

Specialised Cells

• Stem cells become specialised as the embryo grows under the control of genes; this is called differentiation.

Cell Division - Mitosis

• Single fertilised egg → Cell divides by mitosis (DNA replicates then cell splits) → Process repeated as embryo grows

Specialised Cells

• Stem cells become specialised as the embryo grows.

• This is under the control of genes and is called differentiation.

Key points about specialised cells to present:

• Diagram/model of the cell

• Cell function

• How the cell is suited to help carry out its function

Examples of Specialised Cells

• Sperm Cell

• Fat Cell

• Neurones (nerve cell)

• Red blood cells

• Smooth muscle cell from wall of intestine

• Egg cells

• Leaf palisade cells

• Root hair cells

• Xylem cells

• Guard cells from surface of leaf

• Intestinal Mucosal cells

Examples of Specialised Cells and their adaptations

Neurones

• Long and thin.

• Form connections with other neurones.

• Can carry electrical impulses in one direction.

Red Blood Cells

• Large surface area.

• Small diameter.

• No nucleus.

• Contain haemoglobin.

Egg Cells

• Large in diameter.

• Contain stored food.

• Large nucleus.

Palisade Cells

• Large surface area.

• Many tightly packed chloroplasts.

Root Hair Cells

• Thin membrane.

• Large surface area.

Xylem Cells

• Hollow.

• Form long tubes.

• Walls contain lignin.

Intestinal Mucosa Cells

• Large surface area (due to villi)

• Large capillary network

Fungi

• What is a pathogen?

  • A disease causing organism (mostly but not always microorganisms) that stimulates an immune response.

What are the parts of a typical Fungal cell called?

• Cell wall

• Cell membrane

• Nucleus

• Cytoplasm

• Vacuole

• Mitochondria

Yeast

• Used to make bread, wine, and beer.

• Glucose → Carbon dioxide + Ethanol + Energy.

Unicellular Reproduction (Budding)

• Asexual reproduction.

Multicellular Fungus

• Made up of the main body of a fungus is the mycelium, which is made of strands called hyphae.
  *Examples: Mucor and Penicillium.

Characteristics

• Mostly multicellular.

• Have cell walls made from chitin.

• Do not have chloroplasts so don’t photosynthesize.

• Use saprotrophic nutrition.

• Have many nuclei.

• Contain a vacuole.

• Store carbohydrates as glycogen (same form as animals).

Saphrotrophic Nutrition

• Secrete digestive enzymes.

• Enzymes break down large insoluble molecules into small soluble molecules.

• Which diffuse from an area of high concentration outside across the fungus to an area of low concentration inside the fungus.

• Important in decomposition as breaks down dead organic material.

Protoctista

• Video - Introduction to Protoctista

What are Protoctista?

*Most Like Plant or Animal? Explain
*canal - it takes in its food here
*eye spot-detects light here
*Flagellum - uses it to move. It is made in a different way from a bacterium flagellum.
*cell wall
*vacuole store of a carbohydrate similar to starch
*nucleus
*cell membrane
*chloroplast
*cytoplasm
*Euglena

Protoctista

• Protoctista are microscopic, unicellular organisms.

• Some are more like animal cells such as Amoeba.

• A pathogenic example is Plasmodium which causes Malaria.

• Others are more like plants and contain chloroplasts so can photosynthesize.

• These are called Algae (some are multicellular) an example is Cholorella.

Bacteria

Copy And Complete

• Some bacteria are useful to humans like. *Lactobacillius bulgaricus which is used in making yogurt and cheese from milk

• Others are pathogens e.g. Pneumococcus which can cause pneumonia

Bacteria – What They Look Like

• All bacteria are basically one of three different shapes:

  • Rods

  • Spherical

  • Spiral

Bacteria are Unicellular Organisms

• Bacteria cells are about 1/1000th the size of animal or plant cells.

Structure:

• Cell membrane

• Cytoplasm

• DNA

• Cell wall

• Slime capsule (some) made of carbohydrate and protein

• No nucleus, DNA forms a single circular chromosome.

• Plasmid- Small circular ring of DNA. Can contain genes for antibiotic resistance. Can be used in genetic engineering as VECTORS.

• Flagellum- (some) used to move

Bacteria – Reproduction

• Bacteria reproduce very quickly. Two  four eight and so on. . . . . . In a process called binary fission.

• It occurs every 20 minutes.

• The ideal conditions for reproduction are:

  • Moisture (to activate enzymes)

  • Warmth (to increase kinetic energy of the enzymes  collide more  more enzyme substrate complexes form)

  • Oxygen (for respiration)

Binary Fission Exponential Growth!

*20 mins - 2 40 mins - 4 1 hour - 8 1 h 20 mins - 16 1 h 40 mins - 32 2 hours - 64

• If start with 3 = 64 x 3 = 192

• What is going on?

• Why is the bacterial population no longer increasing? Even worse it starts to drop!

• What would Miss Martin say?
  Compete for food, oxygen or water with each other when increase in numbers (intraspecific competition)
  Due to buildup of toxic waste products kills bacteria

Bacteria – Nutrition

• Some bacteria are able to photosynthesize using a form of chlorophyll in their cytoplasm. These are called Autotrophs.

• Most use heterotrophic nutrition and are important decomposers (heterotrophic).

Compare the structures in the different types of cells:

Viruses

Examples of viruses:

• THINK-PAIR-SHARE:
  *3) HIV
  *Disease – AIDS
  *Symptoms - Weakened immune system so susceptible to secondary infections often resulting in death
  *4) Influenza
  *Disease – ‘Flu
  *Symptoms – High temperature, sore throat, runny nose.
  *5) Tobacco Mosaic Virus
  *Disease – Tobacco Mosaic Virus Disease
  *Symptoms - Leaves discolour due to lack to chloroplasts

Key facts about HIV

*False – blood transfusions, sharing needles, mother to child
*True
*False – HIV is the virus which leads to an infection, AIDS is a condition that develops due to the infection
*True
*True
*False – 2.6 million children

The structure of a Virus

• Viruses are very small, approximately 100nm across (1nm = 1/1000 000 of a mm)
  Membrane from host cell. Host cell membrane with host antigens.

Important Questions on Virsus's

• What is the advantage of the envelope to the virus?

• How do you think it works?

• Why is a virus not classed as a living thing? (you must know this for the exams

The envelope is taken from the host cell. It contains the antigens from the host cells, therefore, is less likely to recognised by the immune system of the host as a pathogen.
They are not classed as living things as they are not made of cells. They do not possess the characteristics of living things: MRS C GREN (apart from reproduction, but they use host cells to do this)

Reproduction Cycle

• Draw and annotate each stage of the reproduction cycle:

• Virus attaches to cell membrane

• Virus RNA enters cell

• DNA copy of the RNA is made

• Nucleus makes copies of the virus RNA

• Virus cores are made in the cytoplasm

• New viruses leave the cell and are coated by the cells membrane

Revision

Complete the missing words and match them up!

• M - Producing offspring

• Respiration - Not staying in the same place

• S - Removal of toxic waste products

• C - Increasing in size and mass

• Growth - Either making their own food or eating organisms

• R - Releasing energy from food

• Excretion - Ability to recognise and respond to changes in the environment

• N - Maintain their constant internal environment

Questions

• What does the Cytoplasm, cell wall, chloroplast and cell membrane do?

• Name a way the Sperm cell, Neurone (Nerve), Red Blood Cell, and Root Hair cell are specialised for each function?