Eukaryotes

Question 1

protist

Answer 1

small eukaryotes
eukaryotes that are not plants, animals or fungi
most are unicellular (but not all)
very diverse

Question 2

why was the kingdom Protista abandoned

Answer 2

genetic investigation revealed that many protists had more in common with plants, animals or fungi than with other protists

Question 3

ongoing changes in understanding of phylogeny has changed the way we view the classification of eukaryotes. What are the 4 supergroups of eukaryotes

Answer 3

Excavata
SAR
Archaeplastida
Unikonta

Question 4

Excavates

Answer 4

include protists with modified mitochondria (highly reduced) and protists with unique flagella

Question 5

SAR

Answer 5

highly diverse - Stramenopila, Alveolata, Rhizaria
DNA similarities
diatoms amoebas dinoflagellates

Question 6

Archaeplastida

Answer 6

red and green algae
plants
key photosynthetic species
red and green algae are the closest relatives of plants

Question 7

unikonta

Answer 7

includes animals and fungi

amoeba

Question 8

in endosymbiotic theory where do mitochondria come from

Answer 8

descended from bacterium engulfed by a host cell that was archaean

Question 9

in endosymbiotic theory where did plastids come from

Answer 9

eukaryote engulfed cynobacteria (photosynthetic ) that then evolved into plastids ( a chloroplast is a type of plastid) (primary endosymbiosis)
this gave rise to red and green algae
(cyanobacteria are gram negative and have two cell membranes) - plastids in red and green algae also have two cell membranes
red and green algae engulfed by other eukaryotes (secondary endosymbiosis)

Question 10

what is the closest relative to plants

Answer 10

green algae (protist)  
charophytes - have cuticles and stomata

Question 11

types of plants

Answer 11

non vascular e.g. mosses - liverworts, mosses and hornworts
vascular - 93% of all plant species
Vascular divided into
-seedless - club mosses and ferns (lack seeds / spore forming)
- seed forming - gymnosperms (no casing for seed) and angiosperms (flowering plants seeds develop inside chambers)

Question 12

what traits are shared by fungi

Answer 12

Nutrition -cannot make their own food
fungi do not ingest (no digestive system) - absorbs nutrients from outside their body
Body structure - multicellular filaments and single cells (yeasts)

Question 13

nutrition in fungi

Answer 13

heterotrophs - cannot make their own food
absorb nutrients from their environment
secrete enzymes into their surroundings or use enzymes to penetrate cell walls of other organisms
can digest compounds from wide range of sources living or dead

Question 14

fungi as decomposers

Answer 14

break down and absorb nutrients from non living organic material e.g. logs / corpses / wastes

Question 15

parasitic fungi

Answer 15

absorb nutrients from the cells of living hosts

may be pathogenic

Question 16

mutualistic fungi

Answer 16

absorb nutrients from a host but also give benefits e.g. fungi in digestive tracts

Question 17

yeast

Answer 17

unicellular fungi - single cell

most fungi grow as filaments and relatively few species grow as single celled yeasts

Question 18

hyphae

Answer 18

fungi are made of a network of tiny filaments called hyphae - mushrooms and underground mycelium are continuous networks of hyphae
hyphae consist of tubular cells walls surrounding the plasma membrane and cytoplasm of cells

Question 19

what are hyphae made from

Answer 19

tubular cell walls that surround the nucleus and cytoplasm of cells
cell walls contain chitin (polysaccharide)

Question 20

septa

Answer 20

in fungi hyphae are divided into cells by cross walls called septa (septum)
Septa have pores large enough to allow ribosomes, mitochondria and nuclei to flow from cell to cell

Question 21

mycelium

Answer 21

fungal hyphae form an interwoven mass called mycelium
infiltrates the material on which fungi feeds
maximises surface to volume ratio
just 1 cubic centimetre of soil may contain 1 km of mycelium giving it 300 square cm of surface in contact with the soil

Question 22

mycorrhizae

Answer 22

mutually beneficial relationships between plants and fungi

contain mycelial networks that penetrate the soil further than plant roots / more efficient nutrient acquisition

Question 23

ectomycorrhizal fungi

Answer 23

grow over the plant root but do not penetrate

Question 24

endomycorrhizal / arbuscular fungi

Answer 24

penetrate into the plant cell / extend arbuscules through the root cell