Topic 1 (Cell Biology) Flashcards

Question

How are root hair cells specialised

Answer 1

•Long hairs that stick out of the soil •Large surface area to absorb water and mineral ions

Answer 2

•Long thin tubes so they don’t take up a lot of space but transport water and minerals effectively •Hollow to allow stuff to flow through it

Answer 3

•Long thin tubes so they don’t take up a lot of space but transport water and minerals effectively •Very few organelles to allow stuff to flow through it

Answer 4

Whilst embryonic stem cells can specialise into any cell, adult stem cells can only differentiate into certain cells like blood cells as they are produced in the bone marrow

Answer 5

•Medicine already uses adult stem cells to cure disease e.g stem cells from a healthy persons bone marrow can replace faulty blood cells in sick people who receive them •Embryonic stem cells could be used to replace faulty cells in sick people, you could make insulin producing cells for people with diabetes

Answer 6

•Against stem cell research as they feel each embryo is a potential human life •Embryos can not give consent to be tested on

Answer 7

•In plants stem cells are found in the meristems •Throughout plant life cells in the meristem tissues can differentiate into any type of plant cell •These stem cells can be used to produce clones of whole plants quickly and cheaply •This can be used to save species from extinction or for agricultural purposes

Answer 8

Chromosomes are coiled up lengths of DNA molecules

Answer 9

•Growth and Replication •Mitosis

Answer 10

Before a cell divides, it has to grow and increase the amount of su cellular structures such as mitochondria and ribosomes. It then duplicates its DNA so that there is one copy for each new cell. The DNA is copied and forms an X shaped chromosomes. Each ‘arm’ of the chromosome is an exact copy of the other

Answer 11

Once the cell contents have been duplicated the cell is ready for mitosis. The chromosomes line up in the centre of the cell and the cell fibres pull them apart. Each arm going to an opposite side of the cell. Membranes form around each of the chromosomes and these become nuclei. Lastly the cytoplasm and cell membrane divides to form the two new daughter cells

Answer 12

Binary fission

Answer 13

•Bacteria is grown in a ‘culture medium’ which contains the carbohydrates, minerals, proteins and vitamins they need to grow •Culture medium can be a nutrient solution or agar jelly •Bacteria grown on agar plates will form visible colonies on the surface of the jelly, or will spread out to give an even covering of bacteria •In a school lab temperatures are kept below 25•c to reduce chances of harmful pathogens forming, in an industrial lab temperatures would be much higher so the bacteria grows quicker

Answer 14

•Sterilise the Petri dish (by heating to a high temperature) before use to kill any unwanted microorganisms •If an inoculating loop is used to transfer the bacteria,it should also be sterilised •After transferring bacteria, the Petri dish lid should be taped on to stop pathogens getting into the agar jelly from the air •Petri dish should be stored upside down to stop drops of condensation falling into agar jelly

Answer 15

•Place paper discs soaked in different types (or concentration) of antibiotics on an agar plate that has an even covering of bacteria •The antibiotics should diffuse into the agar jelly. Antibiotic resistant bacteria will continue to grow around the disc but non resistant strains will die. A clear area will be left where bacteria have died called zone of inhibition •Make sure you use a control, one paper disc with no antibiotic •Leave plate for 48 hours at 25•c •The more effective the antibiotic, the larger the zone of inhibition

Answer 16

Diffusion is the net movement of particles from and area of higher concentration to an area of lower concentration along the concentration gradient

Answer 17

Osmosis is the net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration

Answer 18

•The cells on a root grow into ‘hairs’ •Each branch of a root will be covered in millions of these microscopic hairs •This gives the plant a large surface area for absorbing water and mineral ions from the soil •The concentration is usually higher in the cell than out of it so diffusion can not take place •Active transport allows the minerals to be absorbed from a dilute solution to a concentrated solution against the concentration gradient, it requires energy from respiration

Answer 19

Active transport is used in the gut when there is a lower concentration of nutrients in the gut but a higher concentration in the blood

Answer 20

•The job of the lungs is to transfer oxygen into the blood and to remove carbon dioxide •To do this the lungs contain millions of little air sacs called alveoli where gas exchange can take place •As air rushes in through the bronchiole it fills the alveoli, the oxygen them diffuses into the bloodstream and the carbon dioxide diffuses out

Answer 21

They have: •Large surface area to volume ratio •A moist lining for dissolving gases •Walls that are one cell thick (Short diffusion distance) •Good blood supply