Bio Unit 1.2 (Cells)

Question 1

What are the membranes surrounding cells made of and why can’t a light microscope distinguish them?

Answer 1

Phospholipids and proteins, the membranes are too thin to be distinguished by a light microscope

Question 2

What is the advantage of eukaryotic cells having membrane bound organelles?

Answer 2

Harmful chemicals can be isolated and molecules with a particular function can be concentrates to one area

Question 3

Prokaryotic Cell Wall substance

Answer 3

peptidoglycan

Question 3

Prokaryotes

Answer 3

(e.g bacteria cells), basic, smaller structure with no internal membranes and membrane bound organelles, DNA free in cytoplasm

Question 4

Eukaryotic cells

Answer 4

(plants, animals, fungi, protoctists), distinct nuclei, several membrane bound organelles

Question 5

Plant Cell Wall substance

Answer 5

cellulose

Question 6

Respiration in Prokaryotic Cells

Answer 6

mesosomes, infoldings of plasma membrane where respiration occurs

Question 7

Respiration in Eukaryotic Cells

Answer 7

mitochondria site of aerobic respiration

Question 8

Ribosome size in prokaryotic and eukaryotic

Answer 8

70S and 80S

Question 9

DNA present in Prokaryotic

Answer 9

Plasmids are present (rings of DNA)

Question 10

DNA present in Eukaryotic

Answer 10

Chromosome strands in nucleus (linear)

Question 11

Why can’t viruses be seen by a light microscope?

Answer 11

Too small so they can pass through the filters that trap the bacteria

Question 12

Viruses are acellular

Answer 12

no cells, no organelles, no cytoplasm

Question 13

Three components of a virus

Answer 13

nucleic acid, DNA, protein coat (capsid)

Question 14

Viruses that attack bacteria

Answer 14

bacteriophages (eg. T2 virus attacks E.Coli)

Question 15

Size of nucleus

Answer 15

10-20 micrometres

Question 15

Viruses considered living thing?

Answer 15

Viruses can be crystallised, but can reproduce with host (e.g flu in humans, avian flue in birds, TMV in plants)

Question 16

Function of nucleus

Answer 16

Contains DNA which with protein comprises the chromosomes, chromosomes direct protein synthesis

Question 17

Nucleus bounded by…

Answer 17

(2 membranes) nuclear envelope with pores to allow passage of larger molecules(mRNA and ribosomes)

Question 18

The outer membrane of nucleus is continuous with…

Answer 18

endoplasmic reticulum

Question 19

Granular material in nucleus

Answer 19

Nucleoplasm

Question 20

What is nucleoplasm

Answer 20

contains chromatin (coils of DNA bound to protein) - during cell division chromatin condenses into chromosomes

Question 21

Nucleolus

Answer 21

spherical bodies which are the sites of formation of rRNA (constituent of ribosomes)

Question 22

Mitochondria Size

Answer 22

1- 10 micrometres

Question 23

Mitochondria membrane

Answer 23

2 membranes separated by narrow, fluid filled inter membrane space

Question 24

Organic Matrix of Mitochondria

Answer 24

Solution containing many compounds like lipids, proteins, etc.

Question 24

Why is there a small circle of DNA in mitochondria?

Answer 24

So mitochondria can replicate and code for some of its proteins and RNA

Question 25

Size of ribosomes in mitochondria and function?

Answer 25

70S which allow protein synthesis

Question 26

Mitochondria Function

Answer 26

to produce ATP in aerobic respiration (reactions occur in matrix and aerobic respiration)

Question 26

Function of Cristae

Answer 26

Provides large surface area for attachment of enzymes involved in respiration

Question 27

More mitochondria will be in..

Answer 27

Metabolically active cells (muscle cells) as they need lots of ATP so more mitochondria

Question 28

Mitochondria being cylindrical provides…

Answer 28

Large surface area (surface area to volume ratio is bigger than sphere)
Reduces diffusion distance between edge and centre (more efficient aerobic respiration.)

Question 29

Where do you find chloroplasts?

Answer 29

In cells of photosynthesising tissue (in plants highest concentration is in palisade mesophyll cells)

Question 30

Chloroplasts surrounded by

Answer 30

chloroplast envelope

Question 31

Stroma contains…

Answer 31

fluid filled (contains products of photosynthesis such as liquid droplets, starch grains) and takes up large space

Question 32

Ribosomes in chloroplasts are

Answer 32

70S

Question 33

What is found in thylakoids?

Answer 33

chlorophyll

Question 33

DNA in chloroplasts are

Answer 33

circular

Question 34

Each granum has between:

Answer 34

2 and 100 parallel sacs

Question 34

Within stroma

Answer 34

closed, flattened sacs called thylakoids (one stack of thylakoids is a geranium.)

Question 35

Why are thylakoids useful?

Answer 35

Large surface area, efficient from trapping light energy

Question 35

What is endosymbiotic theory?

Answer 35

Describes origin of mitochondria and chloroplasts: 1920’s - mitochondria were once independent bacteria, ancient bacteria engulfed others (maintaining symbiotic relationship) and some of this engulfed bacteria was good at turning glucose and oxygen into ATP (chloroplasts.) Evidence now that chloroplasts and mitochondria have their origins in prokaryotes

Question 36

Endoplasmic Reticulum

Answer 36

System of parallel double membranes forming flattened sacs with cisternae (interconnected fluid filled spaces)

Question 36

Rough ER

Answer 36

ribosomes on outer surface, transports proteins made there, present in large amounts in cells (makes a lot of protein e.g cells making amylase in salivary glands)

Question 37

Smooth ER

Answer 37

membranes lack ribosomes, synthesis and transport of lipids, cells that store carbs, proteins, lipids (e.g in liver, secretory cells) have extensive ER