Cell Theory & Types of Organisms
Name a tool that was used to discover cells and develop cell theory.
Microscopes.
Name one structure you find in plant cells that you do not in animal cells.
Cell wall (or chloroplast or large central vacuole).
What is “classification” in biology?
Organising living things into groups based on similarities and differences.
What is the difference between a vertebrate and an invertebrate
Vertebrates have a spinal chord and back bone, while invertebrates don't.
State MRS GREN in order
Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition
What is a specialised cell?
A cell that has a particular shape or structure so it can perform a specific function in the organism.
What is the function of the nucleus in a cell?
It holds the genetic material (DNA) and controls the activities of the cell.
What is a classification key (or dichotomous key)?
- A tool with paired choices that helps identify an organism by following steps based on its characteristics.
- Yes or no questions
Name all five chordate classes
Mammal, Bird (avian), Amphibian, Fish, Reptile.
State the Linnean classification system in order
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
What is the cell theory?
All living things are made of cells; cells are the basic units of structure and function in living things; all cells come from other cells.
Describe three structures of a plant cell and say what they do.
Chloroplasts – allow photosynthesis, converting light into food; Cell wall – rigid layer outside cell membrane giving support; Large central vacuole – stores water, helps maintain rigidity (turgor), and stores nutrients/wastes.
Why are structural features useful in making classification keys?
Because they are often visible, consistent, and allow us to distinguish organisms by how they look (shape, presence/absence of parts) which makes identification easier.
List three observable structural features you might use to classify different types of plants.
Leaf type (needle-like vs broad), type of roots (taproot vs fibrous), presence or absence of flowers, seed type (naked seeds vs inside fruit), leaf arrangement.
Why would a non-living thing that has some features of MRS GREN not be classified as living?
Living things must possess all features of MRS GREN
Give two examples of specialised cells in plants and two in animals.
Xylem cell: transport water in plants
Phloem cell: transport nutrients in plants
Blood cell: transport oxygen around animal bodies
Nerve cell: transport electric signals around the body
List three similarities and three differences between plant and animal cells.
Similarities: both have nucleus, cytoplasm, cell membrane; both have organelles like mitochondria; both perform life processes. Differences: plant cells have cell wall, chloroplasts, large central vacuole; animal cells do not; animal cells often are flexible/varied shapes, plants often more fixed/rectangular shape; animal cells may have many small vacuoles or none, plant has one large vacuole.
Which organism is a horse?
a. Organism has feathers → go to 2
1b. Organism has hair/fur or scales, and no feathers → go to 3
2a. Can fly; has wings and beak → Organism 1
2b. Cannot fly; adapted for swimming; flippers instead of wings → Organism 2
3a. Has fur/hair → go to 4
3b. Does not have fur/hair; skin covered by scales; usually lives partly in water → Crocodile
4a. Is large, hoofed mammal; eats mostly grass; long legs suited for running; produced by birth (live young) → Organism 3
4b. Small to medium-sized, carnivorous mammal; retractable claws; usually walks on toes; eats meat → Organism 4
Organism 3
What are the differences and similarities between an angiosperm and gymnosperm?
While both are vascular, seed producing plants, Gymnosperms produce naked seeds while angiosperms produce fruit and flowers.
Name 4 of the 6 kingdoms.
Plant, Fungi, Animal, Protists, Bacteria, Archaea
Describe two ways specialised cells in animals and plants differ in structure.
Animal specialised cells often are flexible, have structures like cilia or long extensions (e.g. nerve cells), whereas plant specialised cells may have rigid cell walls, chloroplasts, and large central vacuoles. Also plants may have cells for photosynthesis, support, etc., animals for movement or sensing.
Explain how different structures of plant and animal cells help them perform functions suited to their roles in nature.
Plant cell structures (cell wall for support, chloroplasts to capture light energy, vacuole for water storage and rigidity) enable them to stay upright, make own food by photosynthesis, survive in different water conditions. Animal cells (varied cell shapes, flexible membranes, specialized cells for movement, digestion, etc.) allow animals to move, respond quickly, eat other organisms. These structural differences reflect different roles and lifestyles.
Explain limitations of classification using structural features only, and how scientists improve accuracy.
imitations: similar features can evolve independently (analogous), environment can alter appearance, juvenile/adult forms differ, hidden internal features not visible. Scientists improve by using multiple features, including reproductive and developmental traits, and molecular/genetic evidence.
Can be subjective - what one person observes may different to another person.
Name four of the nine invertebrate phyla
Porifera, Cnidaria, Platyhelminthes, Nematoda, Mollusca, Annelida, Arthropoda, Echinodermata, Rotifera
Name the two domains
Prokaryote and Eukaryote