1. Eukaryotic Cells And Organelles

Question 1

What is a piece of evidence all living things evolved from one common ancestor?

Answer 1

All the cells in living things have the same basic features in common.

Question 2

What is a prokaryotic organism?

Answer 2

A prokaryotic cell (a single-felled organism). They are usually small and simpler.

Question 3

What is a eukaryotic organism?

Answer 3

A organism made up of eukaryotic cells. They are more complex.

Question 4

Give some examples of eukaryotic cells.

Answer 4

Animal, plant, algal and fungal cells.

Question 5

What is an organelle?

Answer 5

A part of a cell with a specific function.

Question 6

What extra organelles do plant cells have that are not found in animal cells?

Answer 6

1. A cellulose wall
2. A vacuole
3. Chloroplasts

Question 7

What are plasmodesmata in plant cells?

Answer 7

Channels for exchanging substances between adjacent cells.

Question 8

What are the differences between algal and plant cells?

Answer 8

Algae can exist as unicellular organisms e.g. Chlorella, or multicellular e.g. seaweed.
The chloroplasts in algal cells are a different shape and size to that of plant cells. For example some algae have one large chloroplast rather than many small chloroplasts.

Question 9

Name the similarities between algal and plant cells.

Answer 9

Algal cells photosynthesise.

Algal cells have the same organelles as plant cells, including a cellulose wall and chloroplasts.

Question 10

How can fungi exist?

Answer 10

Fungi can be multicellular e.g. mushrooms, or unicellular, e.g. yeast.

Question 11

Fungi are a lot like plant cells, with two key differences. Describe these differences.

Answer 11

Their cell walls are made of chitin, not cellulose.

They don’t have chloroplasts because they don’t photosynthesise.

Question 12

Describe the cell surface membrane / plasma membrane.

Answer 12

The membrane is found on the surface of animal cells and just inside the cell wall of fungal, algal and plant cells.
It’s made up mainly of phospholipids and proteins.

Question 13

Describe the function of the cell-surface membrane/ plasma membrane.

Answer 13

It regulates the movement of substances into and out of the cell.
It also has receptor molecules on it which allow it to respond to chemicals like hormones, and other cells.

Question 14

Describe the nucleus.

Answer 14

The nucleus is a large organelle surrounded by a double membrane called the nuclear envelope, which contains many pores.
The nucleus holds chromosomes and one or more structures called a nucleolus.

Question 15

Describe the function of the nucleus.

Answer 15

The nucleus controls the cell’s activities by controlling transcription of DNA. DNA contains instructions to make proteins. The pores allow substances e.g. RNA to move between the nucleus and the cytoplasm. The nucleolus makes ribosomes.

Question 16

Describe the mitochondrion.

Answer 16

They’re usually oval shaped.
They have a double membrane, the inner one of which is folded to form structures called cristae.
Inside is the matrix, which contains enzymes involved in respiration.

Question 17

Describe the function of the mitochondrion.

Answer 17

It is the site of aerobic respiration. Aerobic respiration produces ATP- a common energy source in the cell. Mitochondria are found in large numbers in cells that are very active and require a lot of energy.

Question 18

Describe the chloroplast.

Answer 18

Chloroplasts are small, flattened structures found in plant and algal cells.
They are surrounded by a double membrane, and also contains stacks of membranes called thylakoid membranes that make up structures called grana. Grana are linked up by thin, flat pieces of thylakoid membrane called lamellae.

Question 19

Describe the function of chloroplasts.

Answer 19

Chloroplasts are the site where photosynthesis takes place. Some parts of photosynthesis happen in the grana, and other parts happen in the stroma (the thick fluid inside a chloroplast).

Question 20

Describe the Golgi apparatus.

Answer 20

The Golgi apparatus is a group of fluid-filled membrane-bound flattened sacs. Vesicles are found at the ends of the sacs.

Question 21

Describe the function of the Golgi apparatus.

Answer 21

The Golgi apparatus processes and packages new lipids and proteins. It also makes lysosomes.

Question 22

Describe Golgi vesicles.

Answer 22

The vesicles are small fluid-filled sacs in the cytoplasm, surrounded by a membrane and produced by the Golgi apparatus.

Question 23

Describe the function of Golgi vesicles.

Answer 23

Golgi vesicles store lipids and proteins made by the Golgi apparatus and transport them out of the cell via the cell-surface membrane.

Question 24

Describe lysosomes.

Answer 24

Lysosomes are round organelles surrounded by a membrane with no clear internal structure.
They are a type of Golgi vesicle.

Question 25

Describe the function of lysosomes.

Answer 25

They contain digestive enzymes called lysozyme.
These are kept separate from the cytoplasm by the surrounding membrane, and can be used to digest invading cells or to break down worn out components of the cell.

Question 26

Describe ribosomes and their function.

Answer 26

Ribosomes are very small organelles that float free in the cytoplasm or are attached to the rough endoplasmic reticulum.
They’re made up of proteins and RNA and have no membrane.
They are the site where proteins are made.

Question 27

Describe rough endoplasmic reticulum (RER) and it’s function.

Answer 27

The RER is a system of membranes enclosing a fluid-filled space. The surface is covered with ribosomes.
It folds and processes proteins that have been made at the ribosomes.

Question 28

Describe the smooth endoplasmic reticulum (SER) and its function.

Answer 28

The SER is similar to rough endoplasmic reticulum but with no ribosomes. It synthesises and processes lipids.

Question 29

Describe the cell wall.

Answer 29

It is a rigid structure that surrounds cells in algae, plants and fungi.
In plants and algae its made mainly of cellulose.
In fungi, its made of chitin.

Question 30

Describe the function of the cell wall.

Answer 30

It supports cells and prevents them from changing shape.

Question 31

Describe the cell vacuole.

Answer 31

Found in plants, it is a membrane-bound organelle found in the cytoplasm.
It contains cell sap- a weak solution of sugar and salts. The surrounding membrane is called the tonoplast.

Question 32

Describe the function of the cell vacuole.

Answer 32

It helps maintain pressure inside the cell and keeps the cell rigid. This stop plants wilting. It’s also involved in the isolation of unwanted chemicals inside the cell.

Question 33

How do specialised cells differ from normal cells?

Answer 33

They may have a different shape and number of different organelles to help carry out a specific function.

Question 34

How are epithelial cells in the small intestine adapted to absorb food efficiently?

Answer 34

1. The walls of the small intestine ave lots of finger like projections called villi. These increase surface area for absorption.
2. The epithelial cells on the surface of the villi have folds in their cell surface membranes called microvilli. Microvilli increase surface area even more.
3. They have lots of mitochondria to provide energy for the active transport of digested food molecules into the cell.

Question 35

How are red blood cells adapted to suit their function?

Answer 35

They have no nucleus to make more room for the oxygen-carrying compound haemoglobin.

Question 36

How are sperm cells adapted to suit their function?

Answer 36

They contain a lot of mitochondria to provide the large amounts of energy they need to propel themselves towards an egg.

Question 37

What are tissues?

Answer 37

Groups of specialised cells working together to perform a particular function.

Question 38

What are organs?

Answer 38

Groups of different tissues working together.

Question 39

What is an organ system?

Answer 39

Different organs that are involved in one specific process.

E.g. respiration, transport of blood, digestion of food.