Biology Topic 3

Question 1

What are the two types of cells called?

Answer 1

Eukaryotic and Prokaryotic

Question 2

Describe a Eukaryota cell

Answer 2

Complex cells e.g. animals and plants

Question 3

Describe prokaryotic cells

Answer 3

Smaller and simpler e.g. bacteria

Question 4

What is the nucleus

Answer 4

Surrounded by a double membrane called the envelope, which contains pores enabling molecules to enter and leave the nucleus. The nucleus also contains chromatin, and a nucleolus, which is the site of ribosome production.

Question 5

What is the lysosome

Answer 5

Contains digestive enzymes used to digest invading cells or break down worn out cells.

Question 6

What is the ribosomes

Answer 6

Composed of two subunits. The site of protein synthesis.

Question 7

What is the rough endoplasmic reticulum

Answer 7

A series of flattened sacs enclosed by a membrane with ribosomes on the surface. The RER folds and processes proteins made on the ribosomes.

Question 8

What is the smooth endoplasmic reticulum

Answer 8

A system of membrane-bound sacs. The sER produces and processes lipids.

Question 9

What is the golgi apparatus

Answer 9

A series of fluid-filled, flattened and curved sacs with vesicles surrounding the edges which processes and packages proteins and lipids. It also produces lysosomes.

Question 10

What is the mitochondria

Answer 10

Usually oval shaped and bound by a double membrane called the
envelope. The inner membrane is folded to form projections called cristae, with
matrix on the inside containing the enzymes needed for cellular respiration.

Question 11

What is the centriole

Answer 11

Hollow cylinders containing a ring of microtubules arranged at right
angles to each other. Centrioles are involved in cell division.

Question 12

Explain the protein production and transport in a cell

Answer 12

1. Proteins made at ribosomes.
2. Ribosomes on rER make proteins which are excreted or attached to cell membrane. Free floating ribosomes in cytoplasm make proteins in cytoplasm.
3. New proteins at rER are folded and processed.
4. Proteins transported from rER to golgi apparatus in vesicles.
5. Further processing at golgi apparatus.
6. Proteins enter more vesicles to be transported around cell to be secreted.

Question 13

What is the cell wall

Answer 13

The cell’s rigid outer covering made of peptidoglycan. Provides the cell with strength and support.

Question 14

What is the slime capsule

Answer 14

Protective slimy layer which helps the cell to retain moisture and adhere to surfaces.

Question 15

What is the plasmid

Answer 15

circular piece of DNA.

Question 16

What is the flagellum

Answer 16

A tail-like structure which rotates to move the cell.

Question 17

What is the pilli

Answer 17

hair-like structures which attach to other bacterial cells.

Question 18

What is the mesosomes

Answer 18

Infoldings of the inner membrane which contain enzymes required for respiration.

Question 19

What is the formula for calculating the magnification of an image?

Answer 19

M = size of image

size of real object

Question 20

How do you convert micrometers to millimeters?

Answer 20

Divide by 1000

Question 21

Describe the light microscope

Answer 21

.Use light to form an image
.Maximum resolution of 0.2 micrometers
.Maximum magnification of x1500

Question 22

Describe the electron microscope

Answer 22

.Use electrons to form an image
.High resolution of 0.0002 micrometers
.Maximum magnification of x 1500000

Question 23

What are the two types of electron microscopes?

Answer 23

Transmission-TEM and scanning-SEM

Question 24

Describe the transmission electron microscope

Answer 24

Use electromagnets to focus on beam of electrons which is transmitted through the specimen
Denser parts of the specimen absorb more electrons and look darker
High resolution images so internal structures of organelles are shown
Only used on thin specimens

Question 25

Describe the scanning electron microscope

Answer 25

Scan beam of electrons across specimen
electrons gather at cathode ray tube to form image
3D images
used on thick specimens
lower resolution images

Question 26

Describe multicellular organisms

Answer 26

Made up of lots of different cell types which are organised to work together.

Question 27

Describe the structure of the ovum

Answer 27

.Zona pellucida- protective coating which prevents polyspermy
.Haploid nucleus- so full set of chromosomes is recovered
.Cortical granules- release substances to harden zona pellucida
.Follicle cells- digestive enzymes to break zona pellucida

Question 28

Describe the structure of the sperm

Answer 28

.Mitochondria- provides energy for rotation of flagellum
.Acrosome- contains digestive enzymes to break zona pellucida
.Flagellum- rotates to move cell

Question 29

What is the process of fertilisation

Answer 29

1) The sperm head meets the protective jelly layer around the egg cell called the zona pellucida and the acrosome reaction occurs – enzymes digest the zona pellucida.
2) The sperm head fuses with the cell membrane of the egg cell thus allowing the sperm nucleus to enter the egg cell.
3) The cortical reaction occurs which causes the zona pellucida to harden and prevents polyspermy.
4) The nuclei fuse and a full set of chromosomes is restored, thus forming a diploid zygote.

Question 30

What is meiosis?

Answer 30

A type of cell division that happens in the reproductive organs to produce gametes.

Question 31

How does meiosis happen

Answer 31

1. DNA replicates so there are two identical copies of each chromosome called chromatids
2. DNA condenses