Topic 1 - Nature & Variety Flashcards
What are plants?
Multicellular organisms that can carry out photosynthesis
Plants have cells that contain chloroplasts.
What do plant cells contain that allows them to perform photosynthesis?
Chloroplasts
Chloroplasts are the organelles responsible for photosynthesis.
What type of walls do plant cells have?
Cellulose cell walls
How do plants store carbohydrates?
As starch or sucrose
Examples of plants
Flowering plants e.g. cereal (maize)
Herbaceous legume e.g. peas or beans
What are the defining characteristics of animals?
Multicellular organisms, nervous coordination & able to move from one place to another
What type of carbohydrate do animals typically store?
Glycogen
Which organisms are examples of animals?
Mammals e.g. humans
Insects e.g. mosquitoes or houseflies
What is the structure that makes up the body of fungi?
Mycelium made from thread-like structures called hyphae.
What do hyphae in fungi contain?
Many nuclei.
What is a characteristic of the cell walls of fungi?
Made of chitin.
How do fungi obtain their nutrition?
By extracellular secretion of digestive enzymes and absorption of organic products.
What is the term for the way fungi feed?
Saprotrophic nutrition.
What carbohydrate do fungi typically store?
Glycogen.
Give an example of a multicellular fungi
Mucor (bread mold)
What type of organism is yeast?
Single-celled fungus.
What are protoctists?
Microscopic single-celled organisms
Give an example of a protoctist that resembles an animal cell.
Amoeba
Amoeba is commonly found in pond water.
Which protoctist is known for having chloroplasts?
Chlorella
Chlorella is more plant-like due to its chloroplasts.
What is a pathogenic example of a protoctist?
Plasmodium
Plasmodium is known for causing malaria.
What is a eukaryotic organism?
Organisms with a membrane bound nucleus
What is a prokaryotic organism?
A organism lacking a nucleus and membrane bound organelles
Examples of a eukaryote
Plants, animals, fungi, and protoctists
Example of a prokaryote
Bacteria
Examples of pathogens
Fungi, bacteria, protocticts or viruses
What are bacteria?
Microscopic single-celled organisms.
What are the main components of bacteria?
Cell wall, cell membrane, cytoplasm, plasmids.
Do bacteria have a nucleus?
No, they lack a nucleus.
What type of DNA do bacteria contain?
Circular chromosome of DNA.
Can bacteria carry out photosynthesis?
Some can, but most feed off other living or dead organisms.
What is an example of a bacterium used in yoghurt production?
Lactobacillus bulgaricus.
What shape is Lactobacillus bulgaricus?
Rod-shaped.
What is Pneumococcus known for?
It acts as the pathogen causing pneumonia.
What shape is Pneumococcus?
Spherical.
What are viruses classified as?
Not living organisms
How can viruses reproduce?
Only inside living cells
What types of organisms can viruses infect?
Every type of living organism
What is the size comparison of viruses to bacteria?
Virus are smaller than bacteria
What structural components do viruses have?
Protein coat and one type of nucleic acid
What are the two types of nucleic acids that viruses can contain?
DNA
RNA
Give an example of a virus and its effect on plants.
Tobacco mosaic virus; causes discolouring of tobacco leaves
It prevents the formation of chloroplasts, impacting photosynthesis.
What disease does the influenza virus cause?
Flu
What does HIV stand for, and what disease does it cause?
Human Immunodeficiency virus
AIDS
What is the definition of diffusion?
Diffusion is the net (overall) movement of particles from an area of high concentration to an area of low concentration (down a concentration gradient)
It is a passive process (no energy is needed)
What is the definition of active transport?
It allows cells to move substances from a low concentration to a high concentration (against the concentration gradient)
Requires energy which is released during respiration
What is the definition of osmosis?
The movement of water molecules from a region of high water concentration (dilute solution) to a region of lower water concentration (concentrated solution) through a partially permeable membrane
How do you calculate surface area?
Calculate surface area of one side then multiply by 6
How do you calculate volume?
l x w x h
How do you calculate surface area to volume ratio?
Surface area/volume —> x:1
Dilute solution
High concentration of water molecules (high water potential)
Low concentration of solute/sugar molecules
Concentrated solution
High concentration of solute/sugar molecules
Low concentration of water molecules (low water potential)
What is a partially permeable membrane?
The cell membrane that has tiny holes only allowing certain molecules through
What can get through the membrane?
small soluble substances e.g. oxygen, carbon dioxide, water molecules
What will happen to an animal cell in a dilute solution?
• Water moves into cells so they will burst
• This is because they do not have a cell wall, so there is no turgor pressure
What will happen to an animal cell in a concentrated solution?
It will shrivel
What will happen to a plant cell in a dilute solution?
• Water enters the cells by osmosis
• Cells become turgid
• The cell wall prevents the plant cell from bursting
What will happen to a plant cell in a concentrated solution?
• Water moves out of the cell by osmosis
• Cells become flaccid
• If even more water leaves, the cell becomes plasmolysed, the vacuole and cytoplasm shrink and the cell membrane pulls away from the cell wall
What does the plant cell wall do in relation to the cells shape, and osmosis?
Plant cells are surrounded by a strong cellulose cell wall.
This outer structure keeps the shape of the cell, and can resist changes in pressure inside the cell.
Water can still move into and out of the cell by osmosis.
Which process, diffusion or active transport, requires energy or is a passive process?
Diffusion - passive
Active transport - requires energy (released in respiration)
What does increasing the surface area do to the rate of diffusion?
More area for the substance to travel across, so faster rate of diffusion.
What does decreasing the diffusion pathway/thinner membrane to cross do to the rate of diffusion?
Shorter diffusion distance, so faster rate of diffusion
What does increasing the concentration gradient do to the rate of diffusion?
Faster rate of diffusion
What does increasing the temperature do to the rate of diffusion?
Increases kinetic energy so more collisions, so faster rate of diffusion.
What does smaller particles do to the rate of diffusion?
The faster they can diffuse
What is the concentration gradient?
The steeper the gradient, the greater the difference in concentration.
(Steep - lots of particles on high end)
What can’t get through the membrane?
large solute molecules (e.g glucose, salt etc) have to be carried across the membrane by specific transport proteins.
What is a bacteria’s cell wall made from?
Peptidoglycan
What is a protoctists’ cell wall made from?
Peptidoglycan
