Cell biology

Question 1

Define Eukaryotic cells

Answer 1

Eukaryotic cells contain their genetic material enclosed in a nucleus.

Question 2

Define Prokaryotic cells

Answer 2

In prokaryotic cells the genetic material is not enclosed in the nucleus

They are much smaller than eukaryotic cells

Question 3

Example of eukaryotic cell

Answer 3

Animal cell
Plant cell

Question 4

Example of prokaryotic cell

Answer 4

Bacterial cell

Question 5

Convert mm to micrometre

Answer 5

X1000

Question 6

Convert micrometre to nanometre

Answer 6

X1000

Question 7

What’s a cytoplasm

Answer 7

A jelly like substance where chemical reactions take place

Question 8

What’s a cell membrane

Answer 8

Controls what comes in and out of the cell

Question 9

What’s mitochondria

Answer 9

Where respiration takes place and releases energy

Question 10

What’s a ribosome

Answer 10

Ribosomes are where protein synthesis takes place

Question 11

What’s a chloroplast

Answer 11

Contains chlorophyll and it’s where photosynthesis takes place

Question 12

What’s a cell wall

Answer 12

Contains cellulose and strengthens the cell

Question 13

What’s a vacuole

Answer 13

Contains cell sap and helps give the cell its shape

Question 14

Sperm cell adaptation

Answer 14

Contain genetic information in the nucleus
Have a tail to swim to the egg cell
Have many mitochondria to release energy in order to move.
Contain enzymes allowing them to digest the egg membrane

Question 15

Nerve cell adaptations

Answer 15

Has an axon that carries the electrical impulses from one part of the body to another
The end of an axon has synapses which allow the impulse to pass from one nerve cell to another
Has dendrites which increase the surface area so that other nerve cells can connect more easily.

Question 16

Muscle cells adaptations

Answer 16

Muscle cells can contract
Contain protein fibres which can change the length
Have lots of mitochondria to provide energy for contraction.
Work together to form muscle tissue

Question 17

Root hair cells adaptations

Answer 17

The root hair increased the surface area of the root
Root hair cells do not contain chloroplasts as they are underground

Question 18

Xylem cells adaptations

Answer 18

Have walls that contain lignin which provides support for the plant.
Have dead xylem cells
The end walls are broken down so cells can form a long tube so water and dissolved minerals can flow easily.
Have no nucleus, cytoplasm, vacuole, or chloroplasts making it easier for water and dissolved minerals to flow

Question 19

Phloem cells adaptations

Answer 19

End walls have pores called sieve plates allowing dissolved sugars to move through
Vessel cells have no nucleus and only limited cytoplasm so dissolved sugars can move through
Has mitochondria in the companion cell to provide energy to the phloem vessel cell

Question 20

Problems with light microscopes

Answer 20

Limited magnification
Limited resolution (so it’s blurry)

Question 21

Advantage of electron microscope

Answer 21

Have much greater magnification and resolution than light microscopes

Question 22

Equation for magnification

Answer 22

Magnification= image size/actual size

Question 23

What’s binary fission

Answer 23

Bacteria multiply by simple cell division
One bacterial cell splits into two bacterial cells

Question 24

Formula for number of bacteria after a certain time

Answer 24

Number of bacteria= 2^n(rounds of division)

Question 25

Describe stages of mitosis

Answer 25

In the first stage, the DNA replicates and the cell grows
In the second stage, one set of chromosomes is pulled to each end of the cell. The nucleus divides.
In the final stage, cytoplasm and cell membrane divide to form to daughter cells.

Question 26

Functions of mitosis

Answer 26

Essential for growth and development of multicellular organisms
Takes place when an organism repairs itself
Mitosis happens during asexual reproduction

Question 27

What are stem cells

Answer 27

A stem cell is an undifferentiated cell that can differentiate to form other types of cells

Question 28

What are embryonic stem cells

Answer 28

Cells in the early embryo have not differentiated. They are capable of differentiating into any type of body cell

Question 29

What are adult stem cells

Answer 29

Stem cells that are only found in a few places which can only differentiate into a few types of cells, such as blood cells.

Question 30

Describe Bone marrow transplants

Answer 30

The patients existing bone marrow is destroyed using radiation.
The patient then receives a transplant of bone marrow from a donor.
The stem cells in the bone marrow now divide and form new bone marrow. They also differentiate and form blood cells.

Question 31

Problems with bone marrow transplant

Answer 31

The donor has to be compatible with the patient. Otherwise the wbc produced by the donated bone marrow could attack the patients body.

There is a risk that viruses can be passed from the donor to the patiend

Question 32

What’s therapeutic cloning

Answer 32

An embryo is produced with the same genes as the patient.
Stem cells from the embryo can be transplanted into the patient without being rejected by the patients immune system
Stem cells can then differentiate to replace cells that are not working.

Question 33

What are meristem tissue

Answer 33

These stem cells can differentiate into any type of plant tissue, at any point in the life of the plant.

These can be used to clone plants that are rare in order to stop it from going extinct.

Question 34

Define diffusion

Answer 34

Movement of particles from an area of high concentration to low concentration

Question 35

Examples of molecules that diffuse

Answer 35

Oxygen-diffuse into the cells
Urea-diffuse out of cells and excreted by kidneys

Question 36

Factors affecting the rate of diffusion

Answer 36

Temperature-the higher the temperature the greater the rate of diffusion. This is because particles have more kinetic energy and are moving faster.
Concentration gradient- the steeper the concentration gradient the higher the diffusion rate
Surface area- the larger the surface area of the cell membrane the faster the rate

Question 37

Define osmosis

Answer 37

The movement of water molecules across a semi#permeable membrane from a higher concentration of water to a lower concentration of water

Question 38

Define active transport

Answer 38

The movement of molecules across a semipermeable membrane from a more dilute solution to a more concentrated solution(against the concentration gradient).
This process requires energy from respiration.