Cells, Organs and Life Processes Flashcards
What organism have bigger surface area?
- smaller organisms
What is a prokaryote?
- another term for bacteria
- meaning ‘before nucleus’
What is an organ system?
- a group of organs working together to perform a particular function
- e.g. digestive system breaks up food
Name the parts of a bacterium cell
- a cytoplasm
- a cell membrane surrounded by
- a cell wall
- genetic material floats in the cytoplasm because bacterial cells don’t have a distinct nucleus. Some of the genes are found in circular structures called plasmids.
What happens when the water concentration in a tissue fluid is higher than in the cells fluid?
- the tissue fluid is a hypotonic solution
- the water moves into the cell
What is a tissue?
- a group of similar cels that work together to carry out a particular function
- can include more than one type of cell
- e.g. muscular tissue, glandular tissue, epithelial tissue
What pressure supports plant tissues?
- turgor pressure
What are some plant tissues?
- epidermal tissue: covers the whole plant
- palisade mesophyll tissue: where most of the photosynthesis occurs
- spongy mesophyll tissue: contains big air spaces to allow gases to diffuse in and out of cells
- xylem and phloem: they transport things like water, mineral ions, sucrose around the plant
What happens if a plant does not get enough water?
- cells lose their turgor pressure, they become flaccid and plants start to wilt
- if it is really short of water, the cytoplasm inside its cells starts to shrink and the membrane pulls away from the cell wall
- this is called plasmolysis, and the cell is plasmolysed
- because of the cell wall, the plant doesn’t completely lose its shape
What is osmosis?
- the movement of water molecules across a partially permeable membrane from a region of high water concentration to a region of low water concentration
Where is the xylem in
1) the root
2) the stem ?
the root:
- one of xylem’s functions is support
- roots have to resist crushing as they push through the soil
- xylem is in the centre to give it strength
the stem:
- stems need to resist bending
- the xylem forms a sort of ‘scaffolding’
- phloem is always around the outside of the stem
What happens when the water concentration in a tissue fluid is the same as in the cell fluid?
- the tissue fluid is an isotonic solution
- no net movement
How are villi adapted for food absorption?
- there are millions of villi
- increase the surface area so food is absurd much more quickly
- one-cell thick
- very good blood supply to assist quick absorption
What are palisade leaf cells adapted for and how?
- they are adapted for photosynthesis
- they are packed with chloroplasts. Most of them are crammed at the top of the cell, so nearer the light
- tall shape means a large surface area exposed down the side for absorbing CO2 from the air in the leaf.
- think shape means that a lot can be packed at the top of a leaf
- they are grouped together at the top of the leaf
What are the organs of plants?
- stems
- roots
- leaves
What type of organism is yeast?
- a single-celled organism
- a microorganism
What is diffusion?
- the spreading of the particles of any substance in a solution, or particles of a gas, resulting in a net movement from an area of high concentration to an area of low concentration
- the greater the difference in concentration, the faster the rate of diffusion
Give example of active transport
- plants can absorb ions from a very dilute solution, against the concentration gradient, but needs energy from respiration to work
- taking glucose from low concentrations in the intestines and from low concentration in the kidney tubules
How are alveoli adapted for gas exchange?
- there are millions of alveoli to increase the surface area (about 75m^2 in humans)
- a moist lining for dissolving gases
- very thin walls, one cell thick
- a good blood supply
What type of organism are bacterial cells?
- a single-celled organism
- a microorganism
What happens when a plant is well-watered?
- its cells draw water in by osmosis and becomes swollen
- they are turgid
- the contents of the cell push against the inelastic cell wall, called turgor pressure, helping to support the plant tissues
How are sperm and egg cells adapted for reproduction?
- the main functions of an egg cell are to carry the female DNA and to nourish the developing embryo in the early stages
- egg cell contains huge food reserves to feed the embryo
- when a sperm fuses with the off, the egg’s membrane instantly changes its structure to stop any more sperm getting in, making sure there is the right amount of DNA
- the function of the sperm is to get male DNA to the female DNA.
- has a long tails and streamlined head to help it swim to the egg
- has a lot of mitochondria to provide energy
- also carries enzymes in their heads to digest through the egg cell membrane
Name the parts of a yeast cell
- nucleus (containing genetic material)
- cytoplasm
- cell membrane which is surrounded by a
- cell wall
Describe the parts of an animal cell
- nucleus: contains genetic material that controls the activities of the cell
- cytoplasm: gel-like substance where most of the chemical reactions take place. Contains enzymes that controls these chemical reactions
- cell membrane: holds the cell together and controls the passage of substances into and out of the cell
- mitochondria: most of the reactions for respiration take place here; energy is released during respiration
- ribosomes: where protein synthesis occurs