Studied by 4 people
Give 2 examples of eukaryotic cells ?
plant and animal cells
Define eukaryotic cell ?
a cell which contains genetic material enclosed in the nucleus
Give 1 example of an prokaryotic cell?
bacteria
What is the sizing like between prokaryotic and eukaryotic cells ?
prokaryotic cells are much smaller than eukaryotic cells
List the 2 forms of DNA in a prokaryotic cell in cytoplasm?
loop of DNA, Plasmid rings of DNA
Where is all DNA found in a prokaryotic cell ?
cytoplasm
Define the function of the nucleus ?
to enclose genetic material
Define the role of the cytoplasm ?
watery solution where chemical reactions take place
What is the function of the cell membrane?
controls which molecules enter and leave the cell
Define mitochondria ?
where aerobic respiration takes place
What is the function of ribosome ?
site of protein synthesis
How can ribosome be seen ?
using an electron microscope
What is a chloroplast?
site of photosynthesis
What are plant cell walls made of ?
cellulose
What is the function of a cell wall ?
strengthens the cell
What is the vacuole ?
permanent structure which contains cell sap
What is differentiation?
specialisation of cells
What is the function of a sperm cell ?
to fertilise the ovum
How much DNA does a sperm cell contain ?
half of adult cell
Give 2 adaptions so sperm can swim to the ovum ?
streamlined, long tail
Why do sperm cells contain many mitochondria ?
energy for swimming
Why does the head of the sperm contain enzymes ?
to digest way through outer layer of ovum
What is the function of a nerve cell ?
to send electrical impulses around the body
What is an axon in a nerve cell covered in ?
myelin
Why are the axons in nerve cells covered in myelin ?
speed up transmission of impulses
What are 2 functions of dendrites ?
increase the surface area, other nerve cells can connect easily
What do a group of muscle cells working together form ?
muscle tissue
What is the function of protein fibres in muscle cells ?
can change the length of the cell
What happens to the protein fibres when muscle cells contract ?
protein fibres shorten
Why are there many mitchondria in muscle cells ?
energy for contraction of muscle cells
How do hairs which cover roots help the plant ?
increase surfce area of the roots
What do roots abosrb in plants ?
water and minerals
WHy do root hair cells contain no chloroplast ?
cells are underground
Where are xylem cells located ?
plant stem
What 2 things do xylem cells carry ?
water, minerals
In what direction does xylem carry things between ?
from roots to leaves only
What re the thick walls in xylem cells made up of ?
lignin
What does lignin do ?
provides structural support
Why are there no internal structures in xylem cells ?
so water can flow
In what direction does phloem carry things ?
up and down the plant
What is the role of phloem cells ?
carry dissolved sugars up and down the plant
What are the pores at the end of phloem vessel cells called ?
sieve plates
What are the two cells phloem tubes are made up of ?
phloem vessel cells, companion cells
What is the main difference between vessel cells and companion cells ?
companion cells contain internal structures
What does each phloem vessel cell have ?
companion cell connected by pores
What is the role of companion cells ?
provide energy to vessel cells
List 2 issues with light microscopes ?
limited resolution, limited magnification
What does having a limited resolution cause ?
blurred image
Why are electron microscopes more helpful than light microscopes ?
greater magnification and greater resolution
Define Binary fission ?
division of a cell into two genetically identical cells
How often do Bacteria cells carry out Binary fission ?
once every 20 mins
What are two conditions that can allow Binary fission to occur in ?
right temprature, enough nutrients
How many chromosome pairs are there in a human body cell ?
23 pairs
What do chromosomes contain?
genes
What is the cell cycle?
process of cell growth and division
What are the 2 ways in which cells divide ?
mitosis and meiosis
List 3 things which occur during the first stage of mitosis ?
DNA replicates form 2 copies of each chromosome, cell grows, copies of internal structures
What happens during the second stage of mitosis ?
1 set of chromosomes pulled to each end of the cell, nucleus divides
What occurs during the final stage of mitosis ?
cytoplasm and cell membrane divide
List 3 functions of mitosis ?
growth and development, asexual reproduction, repair of organism
What are embryonic stem cells?
undifferentiated cells that can differentiate into other type of cells
Where are adult stem cells found ?
bone marrow
What type of cells do adult stem cells differentiate into ?
cells found in the blood
define lukemia ?
cancer of the bone marow
List 3 steps to treat lukemia ?
destroy existing bone marrow of patient by radiation, transplant bone marrow from donor, stem cells divide from new bone marrow
List 2 issues with bone marrow transplant ?
donor must be compatible, viruses could pass
List 3 steps of how therapeutic cloning works ?
embryo produced using same gene as patient, stem cells extracted from embryo transplanted into patient with no immune system rejection, in body cells can differentiate to replace
List 2 issues therapeutic cloning can treat ?
diabetes, paralysis
What 2 reasons against embryonic stem cells ?
religious, ethical objections
Where is the meristem tissue found in plants ?
root and bud
What is the function of the meristem tissue ?
can differentiate into any type of plant tissue
How can meristem tissue be used for benefits ?
clone rare plants to stop from going extinct
List 2 things meristem tissues help to do ?
produce clones quick and cheap
Define diffusion ?
spreading out of particles resulting in a net movement from an area of high concentration to an area of low concentration
What role does oxygen play in cells ?
generates energy in respiration
What is the CO2 concetration like inside the cell ?
high
What is urea ?
waste product produced by cells
What is urea excreted by ?
kidneys
Where does diffusion go out of the cell ?
into blood plasma
List 3 things which affect the rate of diffusion ?
concetration gradient, temperature, surface area of membrane
What happens to the rate of diffusion if the concentration gradient is greater ?
diffusion will occur faster
What happens to the rate of diffusion if the temperature is higher ?
greater diffusion
Why is the diffusion greater if temperature is high ?
more kinetic energy in particles
What happens to the rate of diffusion if the surface area of a membrane is large ?
greater diffusion
How do fish get oxygen ?
from water
How do fillaments help gills of fish ?
give gills large surface area
Name an adaption of gills in fish and why ?
thin membrane for short diffusion pathway
Define osmosis ?
diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane
Define dilute solution ?
have high concentration of water
Define concentrated solution ?
have low concentration of water
Define partially permeable membrane ?
a membrane that allows only certain substances to pass through
What is the concetration of water like in the cytoplasm ?
low concetration of water
What happens if an animal cell is placed in a concentrated solution ?
shrink
What prevents plant cells from bursting ?
cell wall
What is a plant cell known as with a higher concentration of water (swollen) ?
turgid
What is a plant cell known as when it shrinks ?
flaccid
Define active transport ?
movement of substances from a dilute solution to a concentrated solution against a concentration gradient needing energy
How do food molecules move into cells in the small intestines ?
through active transport
Give an example of plant cells using active transport ?
magnesium ions move from soil to root hair cells
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