B2 - Cells Flashcards
What are all living organisms made up of? [1]
Cells
What are multicellular organisms? [1]
- Organisms that are made up of many millions of cells
What is a unicellular organism?
Give an example. [1]
- Organisms made up of just a single cell.
- Bacteria
What is cytoplasm? [3]
- Jelly-like substance containing water and dissolved substances like sugar and salts.
- Site of chemical reactions
- Contains organelles (cell parts)
What is a cell membrane? [3]
- A partially permeable (selective) barrier
- Controls what goes in and out of the cell
- Contains receptor molecules
What are ribosomes? [2]
- Tiny structures in the cytoplasm
- Proteins are made here
(only visible with ELECTRON microscope)
What are mitochondria? [3]
- Where respiration happens
- contains enzymes for respiration
- (only visible with ELECTRON microscope)
What is a cell wall? [3]
- Surrounds the cell
- Made of tough fibre called cellulose
- Makes the wall rigid and supports the cell
What is a nucleus? [3]
- Controls the activities of the cell
- Contains DNA
- Contains instructions to make new cells or new organisms
What is a chloroplast? [3]
- Contains green chlorophyll
- Photosynthesis happens here
- Only found in green parts of the plant
What is a vacuole? [2]
- Full of cell sap (watery solution of sugar and salts)
- Helps keep the cell rigid which supports the plant and keeps it upright.
What do plant cells have that animal cells don’t? [3]
- Chloroplasts
- Vacuole
- Cell wall
What do bacteria cells not have? [3]
- Nucleus
- Mitochondria
- Chloroplasts
The cell wall in a bacteria cell is made of what? [1]
Peptidoglycan, not cellulose
What do plasmids do? [1]
Provide extra genes
The DNA in bacteria cells are in what shape? [1]
- Double Helix
- Circular
Describe the function and structure of a red blood cell. [4]
- Transports oxygen
- Cytoplasm contains haemoglobin - a protein which carries oxygen molecules
- NO nucleus = more space for haemoglobin
- Bi-concave disc shape which increases surface area = more absorption of oxygen
Describe the function and structure of a ciliated cell. [3]
- Movement of mucus in the trachea and bronchi
- Hair-like structures called CILIA
- Cilia move mucus and trap the particles to the throat
Describe the function and structure of a palisade mesophyll cell. [3]
- Photosynthesis
- Lots of chloroplasts for maximum photosynthesis
- Column shaped to maximise sunlight absorption
Describe the function and structure of a root hair cell. [3]
- Absorption of water and minerals
- Thin walls for quick water movement
- Root hair increases surface area for maximum water and minerals ions
Describe the function and structure of a sperm cell. [4]
- Reproduction
- Haploid nucleus contains genetic material for fertilisation
- FLAGELLUM (tail) enables swimming for sperm
- Middle part = acrosome contains digestive enzymes so penentration can happen
Describe the function and structure of an egg cell. [5]
- Reproduction
- Cytoplasm contains nutrients for early embryo growth
- Cell membrane changes after fertilisation by a single sperm so that no more can enter
- Jelly coat stops other cells from coming in
- Haploid nucleus contains genetic material for fertilisation
What does HAPLOID nucleus mean?
A nucleus that contains half the normal number of chromosomes.
Describe the function and structure of a neurone cell. [5]
- Conduction of nerve impulses
- Long so that nerves can run to and from different parts of the body to central nervous system
- Extensions and branches for communication with cells, muscles, glands
- AXON = extension of cytoplasm away from the cell body
- FATTY SHEATH = which insulates the nerve cell and speeds up nerve impulse
