living organisms and cells

Question 1

what do plant and animal cells have

Answer 1

a cell surface membrane, cytoplasm and a nucleus

Question 2

what does a pant cell have but an animal cell doesn’t

Answer 2

cellulose cell wall, a vacuole, chloroplasts

Question 3

function of the cell surface membrane

Answer 3

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

Question 4

function of the cytoplasm

Answer 4

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

Question 5

function of the nucleus

Answer 5

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

Question 6

function of the cell wall

Answer 6

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

Question 7

function of the chloroplast

Answer 7

its in the cytoplasm. contains green pigment chlorophyll (absorbs energy from sunlight) helps for the production of glucose by photosynthesis

Question 8

function of the vacuole

Answer 8

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)

Question 9

function of the rough endoplasmic reticulum

Answer 9

made up of flattened membrane with ribosomes on their surface. Sites of protein synthesis, common in cells which make many proteins

Question 10

function of the mitochondria

Answer 10

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.

Question 11

what are specialized cells

Answer 11

cells that have unique/ specific features to perform a specific job /function

Question 12

functions and characteristics of the red blood cell

Answer 12

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.

Question 13

functions and characteristics of the ciliated cells

Answer 13

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.

Question 14

functions and characteristics of the nerve cell

Answer 14

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.

Question 15

functions and characteristics of the sperm cell and egg/ovum

Answer 15

sperm cell- acrosome, midpiece, tail/flagellum, head and nucleus. able to swim
egg/ovum- nucleus, yolk, zona fellucida. has a large food store

Question 16

functions and characteristics of the root hair cell

Answer 16

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

Question 17

functions and characteristics of the xylem cell

Answer 17

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

Question 18

what is diffusion

Answer 18

the movement of particles from a region of high concentration to lower concentration/ down a concentration gradient

Question 19

factors that effect the rate of diffusion

Answer 19

medium (less dense- faster)
temperature (higher- faster)
mass (larger- slower)
surface area (greater- faster)
concentration gradient (greater- faster)

Question 20

what is the end point of diffusion called

Answer 20

equilibrium

Question 21

examples of diffusion in living organisms

Answer 21

• 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

Question 22

what is osmosis

Answer 22

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

Question 23

what do you call a solution with many water molecules

Answer 23

high water potential

Question 24

what do you call a solution with fewer water molecules

Answer 24

low water potential

Question 25

what is the water potential gradient

Answer 25

from right to left. the water flows down a water potential gradient

Question 26

what happens when cell is placed in a solution of lower water molecules

Answer 26

water leaves cell by osmosis

Question 27

what happens when cell is place in a solution of higher water molecules

Answer 27

water enters cell by osmosis

Question 28

how does osmosis occur in plant cells

Answer 28

• 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)

Question 29

how does osmosis occur in animal cells

Answer 29

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

Question 30

what is active transport

Answer 30

can move molecules against a concentration gradient but requires energy and involves protein carriers in membranes

Question 31

examples of active transport

Answer 31

• the uptake of ions by plant root hairs
• the uptake of glucose by epithelial cells of the villi

Question 32

what does turgid mean

Answer 32

when cells are swollen due to a high water content

Question 33

what is turgor pressure

Answer 33

the pressure on the cell wall from the cell membrane pushing upon it.