chapter 2: cells :)

Question 1

what are the differences between a light microscope and an electron microscope?

Answer 1

1. a light microscope can magnify objects only up to 1000x but an electron microscope magnifies up to 200,000x
2. light micrographs: coloured image
   electron micrographs: black and white image

Question 2

what are cell membrane, nucleus and cytoplasm collectively known as?

Answer 2

protoplasm of a cell.

Question 3

what are the organelles of an animal cell?

Answer 3

1. cell surface membrane
2. golgi apparatus
3. ribosomes
4. smooth endoplasmic reticulum
5. rough endoplasmic reticulum
6. nucleus: nucleolus & nuclear envelop
7. cytoplasm
8. mitchondrion
9. small and numerous vacuole

Question 4

what are the organelles of a plant cell?

Answer 4

1. cell membrane
2. golgi apparatus
3. ribosomes
4. smooth endoplasmic reticulum
5. rough endoplasmic reticulum
6. nucleus: nucleolus & nuclear envelop
7. cytoplasm
8. mitchondrion
9. chloroplast
10. vacuoles
11. cellwall

Question 5

what is the structure and function of the cell surface membrane?

Answer 5

structure: - made of lipids and proteins
- surrounds the cytoplasm
function: - partially permeable membrane that controls what enters and leaves the cell

Question 6

what is the function of the cytoplasm?

Answer 6

• a jelly like substance and is where most of the cell activities occur
• contains organelles

Question 7

what is the structure and function of the nucleus?

Answer 7

structure: - surrounded by the nuclear envelope
functions: - controls cell activities: cell growth and repair worn out parts
- essential for cell division
eg. cells such as red blood cells are unable to divide

Question 8

what is the structure and function of the cell wall?

Answer 8

structure: -encloses the entire plant cell and is made of cellulose
- fully permeable
function: - it protects cell from injury and gives the plant cell a fixed shape

Question 9

what are the functions of the nuclear envelope, nucleoplasm and nucleolus?

Answer 9

nuclear envelope: -separates the contents of nucleus from the rest of the cytoplasm
nucleoplasm: dense material within the nucleus
nucleolus: plays a part in making the protein the cell

Question 10

what is the structure and function of chromatin?

Answer 10

structures: -long thread like structures
- made of proteins and compound called deoxyribonucleic acid or DNA

functions: -heredity stored in DNA & contains instructions that a cell needs to carry out activities

*when cells divide, it condense and become highly coiled, > chromosomes

Question 11

what is the structure and function of the rough endoplasmic reticulum?

Answer 11

structure: - network of flattened spaces lined with a membrane
- ribosomes attach on its outer surface
- its connected to the nuclear envelope

function: - transports proteins made by the ribosomes to the golgi apparatus

Question 12

what is the structure and function of ribosomes?

Answer 12

structure: - small round structures
- floating in the cytoplasm or attached to rough endoplasmic reticulum

functions:
- ribosomes attached to the RER usually make proteins that are usually transported out of the cell
- ribosomes lying freely makes protein that is used within the cytoplasm of the cell

Question 13

what is the structure and function of smooth endoplasmic reticulum?

Answer 13

structure: does not have ribosomes attached to its membrane
- more tubular than RER

functions: -synthesises fats and steroids (hormones)
- converts harmful substances to harmless substances> detoxification

Question 14

what is the function of a mitochondrion?

Answer 14

• small oval rod structure
• aerobic respiration occurs in the mitochondrion
• during this, food substances are oxidised to release energy
• energy can be used for cell activities, cell reproduction & cell growth

Question 15

what are chloroplasts and whats the function of it?

Answer 15

• oval structures in the cell
• contains a green pigment called chlorophyll
  > essential for photosynthesis which plants makes food

Question 16

what are vacuoles and what are its functions in plant and animal cells?

Answer 16

• vacuoles are fluid-filled space enclosed by a membrane > it stores substances

in animals - many, small and temporary vacuoles
> stores water and food substances

in plants- large central vacuole and contains cell sap
- contains dissolved substances such as sugars, mineral salts and amino acids
- enclosed by a partially permeable membrane call tonoplast

Question 17

what is the function of red blood cells and how has it adapted to its function?

Answer 17

function: transports oxygen from lungs to the rest of the body

• it has a circular, biconcave shape
  > increase surface area to volume ratio so that oxygen can be taken in and released at a faster rate
• it contains haemoglobin >binds to oxygen and transport it around the body
• it has no nucleus so that is is able to store more haemoglobin for transport of oxygen

Question 18

how has xylem adapted for its function?

Answer 18

• long hollow tube> extending from roots to leaves
• has no cross-walls > to obstruct water flow through the lumen ( hollow space in the vessel)

-do not have protoplasm to offer resistance to the water flow
- the walls are thickened with lignin ( a woody substance) to prevent collapse of vessels

Question 19

how has root hair cells adapted for its function?

Answer 19

• has a long and narrow protrusion/ extension (root hair)
  > increases the surface area to volume ratio for faster rate of diffusion

Question 20

what is a tissue?

Answer 20

• a group of cells with similar structures which work together to perform a specific function

Question 21

what is a simple tissue and what is are some of the examples of it?

Answer 21

• cells of the same kind may group together to form a simple tissue
  eg in humans: muscular tissue & epithelial tissue (skin tissue)
  eg in plants: epidermis ( covers surface of leaves, stems and roots) & mesophyll tissue ( carry out photosynthesis)

Question 22

what is a complex tissue and what are some examples of it?

Answer 22

• contains more than one type of cells
  eg in human: blood (rbc,wbc, plasma, platelets)
  eg in plants: - xylem consists mainly of vessels and dead cells
• phloem tissue consists mainly of sieve tubes and companion cells

Question 23

what is an organ?

Answer 23

• an organ contains more than one type of tissue, all working together for a specific function

Question 24

what is an organ system and what are some examples?

Answer 24

• it consists of several organs working together for a common purpose
• digestive system, circulatory system, respiratory system and transport system

Question 25

what is an organism?

Answer 25

various system together making up the entire body of an organism

Question 26

what is the structure and function of golgi apparatus?

Answer 26

• stack of flattened spaces surrounded by a membrane
• substances from RER fuse with one end of the golgi apparatus and pinches off from the opposite end

function:
- chemically modifies substances made by the ER
- stores and repackages these substances into vesicles for export out of the cell
> move towards the cell surface membrane and fuse, releasing its contents outside of the cell

Question 27

what is differentiation?

Answer 27

• the process by which a cell becomes specialised for a specific function

Question 28

what are some examples of tissues in organs?

Answer 28

humans- stomach:
- muscular tissue- churns and mixes food with digestive juices
- gland tissue- secretes enzymes to digest food
- nervous tissue- detects presence of food and causes the gland tissue to secrete digestive enzymes

plants- leaf:
mesophyll tissue: carries out photosynthesis
xylem: transports water and mineral salts to leaf for photosynthesis
phloem: transports food substances made in the leaf to all the other parts of the plant

Question 29

just read this :)
When cells divide, they make new cells. A single cell divides to make two cells and these two cells then divide to make four cells, and so on. We call this process “cell division” and “cell reproduction,” because new cells are formed when old cells divide. The ability of cells to divide is unique for living organisms.

Answer 29

you can do it!

Question 30

explain the movement of substances made from the ribosomes is transported out of the cell.

Answer 30

• protein synthesised by the ribosomes
  > gets transported to golgi apparatus by rough endoplasmic reticulum
• substances synthesised by the ribosomes fuse with golgi apparatus, releasing its contents
  > substances are modified and repackaged into vesicles
  > pinches off the other end of the golgi apparatus as secretory vescicles and moves to the cell membrane
• vesicles fuse with the cell surface membrane and contents are released outside of the cell