Cells

Question 1

List examples of eukaryotic cells

Answer 1

-plant
-animal
-fungi
-protist (e.g. algae)

Question 2

List an example of a prokaryotic cell

Answer 2

Bacteria

Question 3

List an example of an akaryote (not cells)

Answer 3

Viruses

Question 4

Why is fungi not a plant?

Answer 4

-contains cell walls, but it contains chitin, not cellulose.
-Fungi; do not photosynthesise, so don’t contain chloroplasts.

Question 5

Why is algae not a plant?

Answer 5

Simularities:
- CAN carry out photosynthesis and are very similar to plant cells as they contain the same organelles e.g. chloroplasts and cell wall (often cellulose as well as hemicellulose

Differences:
-plants are multicellular, algae can be uni cellular.Does not exhibit different cells, e.g., roots stems and leaves

Question 6

Which cells contain a membrane bound nucleus and which ones don’t?

Answer 6

Eukatyotes: contains a membrane bound nucleus
Prokaryotes: NO membrane bound nucleus
Akaryotes: Non-cellular. No membrane,no cellulose. Non living.

Question 7

What is the function of the cell surface membrane? (Not classified as an organelle)

Answer 7

Controls exchange between the cell and its environment. It is selectively permeable, made up of a phospholipid bilayer with many transport proteins embedded in it and receptors for cell recognition and attachment. It is fluid allowing endo- and exo-cytosis.

Question 8

What is the structure of mitochondria?

Answer 8

-double membrane. The inner membrane is folded to form cristae (large surface area for ATP synthesis).
-Intermembrane space. Contains a high concentration of hydrogen ions.
-matrix. Containing circular DNA and 70s ribosomes used to make proteins and self replication.

Question 9

What is the function of mitochondria?

Answer 9

-site of aerobic respiration, using oxygen to make ATP. Many found in cells with a high ATP requirement eg muscle cell’s for contraction.

Question 10

Exam type of question: why do mitochondria appear in different shapes?

Answer 10

-They are 3D and so sit at different angles.
-can appear round or lozenge shape depending on angles.
- ‘they have been cut on different planes’.

Question 11

What is the structure of chloroplasts?

Answer 11

-Double membrane. Inner membrane folded into thylakoids. Thylakoids stacked into into grana. Photosynthetic pigments e.g. chlorophyll located on these membranes. This is the sight of the light dependent reactions.
-stroma. Contains circular DNA and 60s ribosomes used to make proteins and self-replication. It is the site of the light independent reactions. Often contains starch grains (amyloplasts)

Question 12

What is the function of chloroplasts?

Answer 12

Site of photosynthesis. Found in plant and algal cells.

Question 13

What is the structure of ribosomes?

Answer 13

-Ribosomes are composed of 2 subunit, one large and one small which are each made up of only rRNA and protein (no membranes).
-In eukaryotic cells the ribosomes are bigger than in prokaryotic cells (sometimes referred to as 80s. In prokaryotic cells they are smaller 70s)

Question 14

What is the function of ribosomes?

Answer 14

-site of protein synthesis
-site of translation

Question 15

What is the endoplasmic reticulum?

Answer 15

System of flattened membrane bound sacs called cisternae found throughout the cell.

Question 16

What is the function of rough endoplasmic reticulum (RER)

Answer 16

-covered in ribosomes. Proteins are synthesised here and transported/folded in the cisternae.

Question 17

What is the function of the smooth endoplasmic reticulum (SER)?

Answer 17

No ribosomes. Lipids and steroids are synthesised here.

Question 18

What is the structure of the golgi apparatus?

Answer 18

A stack of dynamic flattened cisternae formed from vesicles from the RER.

Question 19

What is the function of the golgi apparatus?

Answer 19

Packages/ modifies proteins received from the RER.
In the cisternae the proteins are modified e.g. to form glycoproteins and packaged into vesicles which bud of to be transported either to another part of the cell or out of the cell (exocytosis/secretion). If the vesicles contain digestive (hydrolytic) enzymes they can form lysosomes.

Question 20

What is the structure of lysosomes?

Answer 20

Spherical membrane bound sacs containing lysozymes (hydrolytic enzymes)

Question 21

What is the structure of the vacuole?

Answer 21

Plant cells: all contain a large permanent vacuole surrounded by a membrane called the tonoplast.
Animal cells: contain vacuoles but they are small and temporary.

Question 22

What is the function of of the vacuole?

Answer 22

Plant cells: function as storage sites e.g. contains the pigment anthocyanin in beetroot cells.
Animal cells: they may act as contractile vacuoles or they may be formed in phagocytosis. Contracts it back out, doesn’t fill with water.

Question 23

What is the function of the cell wall?

Answer 23

Found outside the cell membrane. It gives the cell shape and prevents it from bursting. It is fully permeable to water and solutes.

Question 24

What is the cell wall made out of In the following…
-Plant/ algal cells
-fungal cells
-prokaryotic cells

Answer 24

Plant/algal cells- cellulose
Fungal cells- chitin
Prokaryotic cells- murein

Question 25

What is plasmodesma?

Answer 25

Between the cell walls in plants there are often plasmodesma (plural: plasmodeta). These provide cytoplsmic continuity between plant cells, allowing rapid transport of material.

Question 26

Outline the role of organelles in the production, transport and release of proteins from eukaryotic cells (exam question)

Answer 26

1. DNA in nucleus is code (for protein) 2. Ribosomes/ RER produce (protein) 3.mitrochindria produce ATP for protein synthesis 4.golgi apparatus package/ modify Or Carbohydrate added/ glycoprotein produced by golgi apparatus 5. Vesicles transport OR RER transports 6.(vesicles ) fuse with cell(-surface) membrane.

Question 27

What us a tissue. List examples:

Answer 27

-aggregation of simular cells carrying out the same function. -epithelial tissue, endothelial tissue, cardiac tissue.

Question 28

What is an organ? List examples

Answer 28

-aggregation of several tissues to perform a particular function for the whole organism. -lung, liver, leaf, root

Question 29

What Is an organ system? List examples

Answer 29

-several organs working together -circulatory system (has the heart, arteries and veins)

Question 30

Explain how the epithelial cells in the small intestines are specialised.

Answer 30

Cells lining the walls of the small intestines are specialised to maximise absorption of small soluble molecules into blood. They have microvilli to increase surface area, many mitochondria so lots of aerobic respiration to make ATP for active uptake of molecules and many specific protein carriers in the cell membrane.

Question 31

Compare eukaryotic and prokaryotic cells. 7 marks

Answer 31

-prokaryotic cell is much smaller than a eukaryotic cell -prokaryotic cell has a cell wall but eukaryotic cell does not -eukaryotic cell has a nucleus, prokaryotic does not (has dna loop instead/ lose dna) -prokaryotic cell lacks membrane bound organelles but eukaryotic cell has them. -prokaryotic ribosomes are smaller (70s) than eukaryotic (80s) -prokaryotic dna is circular, eukaryotic is linear -prokaryotic dna I naked whereas human dna is bound to histones/ proteins.

Question 32

Describe the structure and function of the nucleus

Answer 32

Nuclear envelope/ double membrane Nuclear pores in membrane Chromosomes/ chromatic (linear) dna with histones Nucleolus/ nucleoli Holds/stores genetic information for production of proteins Dna replication or interphase Production of mRNA/ tRNA or transcription Production of rRNA/ribosomes

Question 33

Name the main polymer that forms the following cell walls: -plant cells -fungal cells

Answer 33

-cellulose -chitin

Question 34

Describe the role of ONE named organelles in digesting these bacteria

Answer 34

-lysosomes -fuse with vesicles -release hydrolytic enzymes

Question 35

Identify two organelles in cells that enable the production of glycoproteins

Answer 35

RER/ribosomes and golgi apparatus

Question 36

Give two structures found in all prokaryotic cells and in all eukaryotic cells

Answer 36

- cell surface membrane - ribosomes (not 70s) - cytoplasm -DNA