L1: Introduction to Plant Biology

Question 1

Why are plants important?

Answer 1

Without plants, life on Earth would not exist.
- Primary source of food for people and animals
- Produce oxygen
- Help cool the Earth
- Renew the air
- Slow wind speed
- habitat for wildlife
- Beautify surroundings
- Perfume the Earth
- Furnish building materials and fuel
- Medicine source
- Dyes

Question 2

Which domain are plants located in?

Answer 2

Eukarya

Question 3

How many Eukaryotic species are there on Earth?

Answer 3

8.74 million
(9 million)

Question 4

Around how many species of plants are there? (what percentage are flowering plants?)

Answer 4

280000 species
(90% are flowering plants)

Question 5

What is a plant?

Answer 5

• multi-cellular
• eukaryotic
• sexually and asexually reproducing
• cellulose-rich cell walls
• immobile
• autotrophs (unless they are paracytic!)

Question 6

What are the advantages for plants for living on land?

Answer 6

• high light access
• high CO2 concentration
• high space (at first)
• no predators (at first)

Question 7

What are the challenges for plants for living on land?

Answer 7

• low water availability
  (risk of dehydration)
• support (must evolve roots, to be stable and obtain nutrients)
• location of nutrients (soil or atmosphere, must adapt to accept in a different way).
• high and light UV levels

Question 8

What are some plant adaptations?

Answer 8

• developed roots
• hard or flexible stems
• leaves
• defence (toxins, alkaloids, antifeedants, tannins)
• support (lignin (strengthens cell walls))
• UV protection (flavonoids)

Question 9

What is lignin?

Answer 9

• most abundant aromatic biopolymer on Earth
• exists in plant cell walls
• strengthens the cell wall

Question 10

How are plants organised?

Answer 10

Plants are highly organised!
1) cells
2) tissues
3) organs
4) organisms
5) population
6) community
7) ecosystem

Question 11

What processes do plants undergo?

Answer 11

Photosynthesis and Respiration

Question 12

What are the plants functions of life?

Answer 12

Growth
Development
Reproduction (sexual (pollination) and asexual (vegetative propagation))

Question 13

What are the factors which plants react to? What is this process called?

Answer 13

Planst react to external environmental stimulus.
This is called TROPISM.

Question 14

What are the two types of reactions to tropisms?

Answer 14

Positive (+): response towards the stimulus
Negative (-): response away the stimulus

Question 15

What are the different types of tropisms?

Answer 15

Phototropism (light)
Gravitropism (gravity)
Hydrotropism (water)
Chemotropism (chemicals)
Thigmotropism (touch)

Question 16

What are the differences between plants and animals?

Answer 16

Growth: in plants, growth is indefinite, in animals growth is definite.

Excretion: plants produce less waste products, and do not have a specialized excretory system. animals produce more metabolic waste and have special excretory organs.

Respiration: plants have lower respiration than animals.

Nutrition: plants are autotrophic, while animals are heterotrophic.

Movement: plants cannot move (only in growth), while animals move relatively quickly.

Immunity: plants might have immune systems, but animals certainly have immune systems.

Structure: plants have cell walls, and assimilate starch. animals do not have cell walls, and assimilate glycogen.

Injection: plants absorb substances, while, animals swallow food.

Response: plants do not have receptors and nervous systems. plants are less sensitive and respond more slowly. animals have receptors and a nervous system, therefore, the react quickly.

Question 17

What are the similarities between plant and animal cells?

Answer 17

Both contain:
- nucleus
- nuclear envelope
- chromosomes
- cytoplasm
- mitochondria
- cell membrane

Question 18

What are the differences between plant and animal cells?

Answer 18

• plants have rigid cell walls
• plants contain plastids
• plants contain large vacuoles
• plants are regular in shape (animal cells are irregular)

Question 19

How are functional cellular substances classified in plants?

Answer 19

1) constructional (proteins, fats, carbohydrates)
2) reserved nutrients (stored for unfavourable periods)
3) metabolic wastes (crystals of salts)
4) metabolites to resist against insects, herbivores and animals
5) organic compounds
6) inorganic compounds (water, mineral salts, acids)

Question 20

Explain cell walls.

Answer 20

COMPOSITION:
- plant = cellulose
- fungi = chitin
- thin layer rich in PECTIN (glues cells together)

FUNCTION:
- cells exoskeleton for support and protection

Question 21

Cell wall composition/division?

Answer 21

• Middle lamella (with PECTIN which glues cells together)
• Primary wall (small amount of cellulose)
• Secondary wall (don’t always contain cells) (cellulose)

Question 22

What is the protoplast composed of?

Answer 22

water 70%-80%
proteins 10%-20%
lipids 2%-3%
carbohydrates 1%-2%
mineral salts <1%

Question 23

What are the different types of plant vacuoles and vesicles?

Answer 23

• transport vesicles
• food vacuole
• storage vacuole
• central vacuole
• contractive vacuole

Question 24

What is the function of the food vacuole?

Answer 24

store newly ingested food until lysosomes can digest it

Question 25

What is the function of the contractile vacuole?

Answer 25

pump out excess water

Question 26

What is the function of the central water vacuole?

Answer 26

• make up 90% of cell volume
• water regulation
• storage of ions
• storage of hydrophilic pigments

Question 27

What is the function of the storage vacuole?

Answer 27

stores pigments and toxic substances

Question 28

What is the function of the transport vacuole?

Answer 28

• move materials from one organelle to another
• move materials from one organelle to the plasma membrane
  (exocytic vesicles transport materials to the plasma membrane for export)
  (endocytic vesicles transport materials from the outside of the cell to the plasma membrane for import)