GCSE AQA BIOLOGY TRIPLE -TOPIC 1

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