living organisms and cells Flashcards
what do plant and animal cells have
a cell surface membrane, cytoplasm and a nucleus
what does a pant cell have but an animal cell doesn’t
cellulose cell wall, a vacuole, chloroplasts
function of the cell surface membrane
it surrounds the cytoplasm. It controls the entry and exit of dissolved substances and separates the cell’s contents from its surroundings. Are strong but very flexible
function of the cytoplasm
jelly-like substance. mostly water with proteins and other chemicals dissolved in it. Metabolic reactions take place in the cytoplasm. (Animal) often denser, with many more organelles and dissolved substances. (Plant) contains water and dissolved substances such as sugars and salts
function of the nucleus
contains the genetic material (DNA which makes up genes on he chromosmes). This carries the coded instructions for controlling the activities and characteristics of the cell. Chromosome only visible during cell division
function of the cell wall
outside the cell surface membrane. Made up of cellulose. It provides structual support and stops it from bursting when it takes up a lot of water. Is freely premeable to water and dissolved substances
function of the chloroplast
its in the cytoplasm. contains green pigment chlorophyll (absorbs energy from sunlight) helps for the production of glucose by photosynthesis
function of the vacuole
it is not always present. A membrane separates it from the rest. Contains cell sap which contains water, sugars, amino acids and other substances. It is a storage area (ions and molecules)
function of the rough endoplasmic reticulum
made up of flattened membrane with ribosomes on their surface. Sites of protein synthesis, common in cells which make many proteins
function of the mitochondria
made up of membranes which provide a large surface are for aerobic respiration reactions, It releases energy needed to perform work in cell, common in cells that require a lot of energy.
what are specialized cells
cells that have unique/ specific features to perform a specific job /function
functions and characteristics of the red blood cell
no nucleus, has haemoglobin, biconcave shape. Hemoglobin carries oxygen from your lungs to the tissues where aerobic respiration occurs. no nucleus, leaving more space making it flexible, squeezing through the tiniest of blood capillaries. Biconcave shape gives them a large surface area speeding up the rate of which oxygen can move into and out of them.
functions and characteristics of the ciliated cells
have cilia. Found in the lining of our trachea and bronchi. has layers of tiny hairs which can move and push mucus from one place to another. the mucus traps bacteria and dirt particles in the air that you breathe in, so the cilia are helping to keep this out of your lungs.
functions and characteristics of the nerve cell
dendrites, axon, cell body and carries signals. conducts nerve impulses. carries signals, signal goes from dendrite to axon end. the many branched ending can connect with many other cells.
functions and characteristics of the sperm cell and egg/ovum
sperm cell- acrosome, midpiece, tail/flagellum, head and nucleus. able to swim
egg/ovum- nucleus, yolk, zona fellucida. has a large food store
functions and characteristics of the root hair cell
central vacuole, cell wall, hair, cytoplasm. Found on the outside of plant roots. they help anchor the plant to the solid and absorb water and mineral ions from the soil. the cell has a long extension (a root hair) which increases the surface area for the absorption of minerals
functions and characteristics of the xylem cell
cell wall, sieve plate, bands of lignia. Are dead cells. responsible to transport water and mineral ions from the roots to all the other parts of the plant. they also help support the plant. the cell has no cytoplasm (water can pass freely), no end wall (can form a continuous tube). lignia strengthens walls is waterproof
what is diffusion
the movement of particles from a region of high concentration to lower concentration/ down a concentration gradient
factors that effect the rate of diffusion
medium (less dense- faster)
temperature (higher- faster)
mass (larger- slower)
surface area (greater- faster)
concentration gradient (greater- faster)
what is the end point of diffusion called
equilibrium
examples of diffusion in living organisms
- a plant absorbs CO2 from its surroundings by diffusion, the CO2 passes through leaf to the photosynthesising cells and diffuse
- the lungs, oxygen enters the blood by diffusion. continuous movement of blood keeps a high concentration gradient between air and blood
- glucose and amino acids pass from inside the gut into the blood, by diffusion
-mineral ions from soil are absorbed by plant roots by diffusion and active transport - oxygen produced by photosynthesis diffuses out of plant into air. They enter the lungs which then diffusion is sped up because the blood has thin surfaces with very large surface area
what is osmosis
osmosis is a special kind of diffusion, involving water molecules. The diffusion of water molecules from a region of higher concentration of water molecules to a region of lower concentration of water molecules, down a water potential gradient, through a partially premeable membrane
what do you call a solution with many water molecules
high water potential
what do you call a solution with fewer water molecules
low water potential
what is the water potential gradient
from right to left. the water flows down a water potential gradient
what happens when cell is placed in a solution of lower water molecules
water leaves cell by osmosis
what happens when cell is place in a solution of higher water molecules
water enters cell by osmosis
how does osmosis occur in plant cells
- water enters a plant cell by osmosis, cytoplasm swells until it pushes against the cell wall
- cell will not permenantely damaged by entry of water as the cell wall is supporting is. It is turgid (firm)
- water leaves a plant cell by osmosis, cytoplasm shrinks but cell wall still is supporting. it is flaccid (floppy)
how does osmosis occur in animal cells
animal cells have no cell wall, just a membrane
- in a solution of lower water potential, the cell loses water and shrinks and becomes crenated
-in a solution of same water potential as the inside of the cell, the cell is in equilibrium
- in a solution of higher water potential, the cell takes in water, swells and bursts. The contents of the cell escapes and the membrane is just left. The cell dies
what is active transport
can move molecules against a concentration gradient but requires energy and involves protein carriers in membranes
examples of active transport
- the uptake of ions by plant root hairs
- the uptake of glucose by epithelial cells of the villi
what does turgid mean
when cells are swollen due to a high water content
what is turgor pressure
the pressure on the cell wall from the cell membrane pushing upon it.
