B1 cell structure and transport

Question 1

what is the equation for magnification

Answer 1

size of image / size of real object

Question 2

what is magnification

Answer 2

how many times larger the image is than the real object

Question 3

advantages of an electron microscope

Answer 3

a better resolution
structures inside mitochondria and chloroplasts can be seen and scientists can understand how they work
ribosomes can be seen and their role of making proteins can be studied

Question 4

what is the function of a nucleus

Answer 4

controls cell activities and contains the genetic material

Question 5

what is the function of the cytoplasm

Answer 5

where all chemical reactions take place

Question 6

what is the function of the cell membrane

Answer 6

controls the passage of substances coming in and out the cell

Question 7

what is the function of mitochondria

Answer 7

where aerobic respiration takes place

Question 8

what is the function of ribosomes

Answer 8

where proteins are synthesized

Question 9

what is the function of a cell wall

Answer 9

made of cellulose which strengthens the cell

Question 10

what is the function of the vacuole

Answer 10

filled with cell sap and keeps the cell rigid

Question 11

what is the function of chloroplasts

Answer 11

contain a green substance called chlorophyll and this absorbs sunlight by photosynthesis

Question 12

what is a bacterial cell

Answer 12

prokaryotic cell

Question 13

name three differences between a prokaryotic cell and a eucaryotic cell

Answer 13

prokaryotic cells are much small
the genetic material is not enclosed in a nucleus
genetic material is a single loop of DNA called plasmids
they do not contain mitochondria or chloroplasts

Question 14

what is a flagella

Answer 14

tail like structure which moves the bacterium

Question 15

what adaptions does a nerve cell have

Answer 15

long axons carry the nerve impulse from one place to another
Dendrites make connections to other nerve cells
the nerve endings or synapses are adapted to pass the impulses to another cell or between a nerve cell and a muscle in the body using special transmitter chemicals

Question 16

what adaptions does a muscle cell have

Answer 16

they contain special proteins which slide over each other which make the fibers contract
they contain many mitochondria which are needed to transfer the energy for chemical reactions that take place as the cell contract and relax
they contain glycogen, a chemical which can be broken down and used in cellular respiration by the mitochondria to transfer energy needed for fibers to contract

Question 17

what adaptions do sperm cells have

Answer 17

a long tail which moves to side to side to move through water or the female reproductive system
the middles section is full of mitochondria which transfers the energy needed for the tail to work
the acrosome stores digestive enzymes for breaking down the outside layer of the egg
a large nucleus which contains the genetic information which needs to be passed on

Question 18

what adaptions do root hair cells have

Answer 18

increase surface area for water to move into the cell
a large vacuole which speeds up the movement of water by osmosis
they have many mitochondria which transfer the energy needed for active transport

Question 19

what adaptions do photosynthetic cells have

Answer 19

contain chloroplast which trap light needed for photosynthesis
usually in layers in leaves and outer layer of stem to absorb as much light a possible
they have a large vacuole

Question 20

what adaptions do xylem cells have

Answer 20

They lose their end walls so the xylem forms a continuous, hollow tube.
They become strengthened by a substance called lignin . Lignin gives strength and support to the plant

Question 21

what adaptions do phloem cells have

Answer 21

:

Sieve tubes - specialised for transport and have no nuclei. Each sieve tube has a perforated end so its cytoplasm connects one cell to the next.
Companion cells - transport of substances in the phloem requires energy. One or more companion cells attached to each sieve tube provide this energy. A sieve tube is completely dependent on its companion cell

Question 22

what is diffusion

Answer 22

diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration

Question 23

give 3 examples of diffusion

Answer 23

oxygen and carbon dioxide diffuse during gas exchange lungs gills and plant leaves
urea diffuses from cells into blood plasma for excretion by the kidney
digested food molecules from small intestine diffuse into the blood

Question 24

what are the factors affecting diffusion

Answer 24

concentration gradient
temperature
surface area of the membrane

Question 25

what is osmosis

Answer 25

the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane

Question 26

what is active transport

Answer 26

moves substances across the concentration gradient from an area of low concentration to an area of high concentration

Question 27

explain the need for exchange surfaces
and a transport system in multicellular organisms

Answer 27

In multicellular organisms, surfaces and organ systems are
specialised for exchanging materials. This is to allow sufficient
molecules to be transported into and out of cells for the organism’s
needs.

Question 28

How is the effectiveness of gas exchange surfaces increased

Answer 28

The effectiveness of an exchange surface is increased by:
* having a large surface area
* a membrane that is thin, to provide a short diffusion path
* (in animals) having an efficient blood supply
* (in animals, for gaseous exchange) being ventilated.