Biodiversity (plants)

Question 1

Define being alive

Answer 1

Need to capture resources from environment, grow + reproduce yourself

Question 2

Which kingdoms are contained within Eukarya?

Answer 2

Protista, Chromista, Plantae, Fungi, Animalia

Question 3

LUCA

Answer 3

Last universal common ancestor
- possesses characteristics shared by all living organisms today
- has DNA, RNA, proteins, cell mem., systems for capturing light energy, carbs + enzymes

Question 4

2nd law of thermodynamics

Answer 4

Total entropy of isolated system can only increase over time (order->disorder) so life uses energy to maintain + reproduce itself in orderly fashion

Question 5

Stanley miller experiment

Answer 5

1953 heating cooling mimicked conditions Earths est. 4 billion years ago.
Methane, hydrogen, ammonium -> organic matter (glycine produced)
so simple chemicals need energy to form complex structures

Question 6

Chemotrophs

Answer 6

Harness energy from chemicals (use ATP), reactions all exothermic

Question 7

Peter Mitchell Nobel prize 1978

Answer 7

Chemiosmotic hypothesis - energy harnessed by ETC + used for H+ pump to set up pH conc. gradient so h+ diffuse through F type ATPase
feature of LUCA + found in Archaea +Bacteria
- needs oxidants + reductants

Question 8

Archaean photosynthesis

Answer 8

Bacteriorhodopsin (retinal) has red colour + used to store photons (energy), cis-trans isomerisation driven by light moves 2H per photon

Question 9

Bacterial photosynthesis

Answer 9

Uses chlorophyll, has photosynthetic reaction centres which absorb light resulting in e transfer along ETC

Question 10

What are the two types of bacterial reaction centres?

Answer 10

Fe-S (found in green sulphur bacteria + heliobacteria)
Fe (cytochrome) can bind to H2S (found in purple sulphur + green non-sulphur bacteria)

*cyanobacteria only bacteria to have both types of reaction centres

Question 11

How did oxygen evolving complex form?

Answer 11

Lateral gene transfer -> reaction centres combined + began to work together
allowed oxidation of water

Question 12

Evidence for oxygen production in cyanobacteria

Answer 12

Fossils - stromatolites formed by growth of microbial mats w/ bands of iron oxides
Oxidation of metals -> O2 in atmosphere
Huronian Ice age after oxygen, as CO2 formed + is weaker than methane (CH4)

Question 13

Pros and cons of oxygen

Answer 13

Pros - ozone layer forms preventing UV reaching surface allowing life outside of water

Cons - superoxide (free unpaired e), hydrogen peroxide (reactive, used in bleach, hydroxyl radical (very reactive) - Fenton reaction

Question 14

Phagocytosis (1st heterotrophs)

Answer 14

aerobic respiration more efficient so allows cells to evolve + engulf smaller ones

Question 15

When did complex structures appear in eukaryotes?

Answer 15

2 billion yrs ago, from Archaea
- Lokiarchaeota possess traits of eukaryotes including phagocytosis

Mitochondria + chloroplasts result of single endosymbiotic event
archaea consumed aerobic proteobacterium + cyanobacterium

Question 16

Sexual reproduction green alga (Chlamydomonas reinhardtii)

Answer 16

Haploid most of the time, mitosis gives 4 daughter cells, reproduce sexually when stressed
Two types of gametophytes (mt+ and mt-)
Forms persistent zygospore - diploid, inactive

Question 17

First land plants (pros and cons)

Answer 17

Coincided w/ increased O2, followed Cambrian explosion
Pros - new spaces, higher pCO2
Cons - lack of water, no current to aid reproduction

Question 18

Give examples of bryophytes

Answer 18

Liverworts - dominant gametophyte, rhizoids grow down + absorb water, sperm swim form male to female gametophores so sporophyte grows on gametophore

Stomata + vascular tissue in mosses + hornworts

Moss - more complex leaf structure , simple water conducting tissues, ombotrophic (absorbs nutrients from water), sporophyte grows well above gametophyte

Hornworts - presence of cyanobacteria in clefts, symbiosis w/ nitrogen fixer

Question 19

Problems with bryophyte

Answer 19

Poor ability to capture + retain water, poor water transport + limited uptake of nutrients, limited height so needs to be near surface

Question 19

Rhynie Chert

Answer 19

410 Mya, fossils studied by Lang
preserved fossils of different species
features include vascular bundles, mycorrhizal associations (symbiotic relationship)

Question 20

Lycopodiophyta

Answer 20

inc. spike moss, quillwort, clubmoss (not mosses)
-> reproduce by spores, alternation of generations, sporophyte dominant + photosynthetic
*increasing development of larger more dominant sporophyte

Question 21

Tracheids

Answer 21

Type of water conducting cell in xylem, found in vascular plants
1’ growth cell division at tip - cell elongation
2’ growth cell division at cambia, structures become thicker eg. lycophytes evolved thick stems w/ lignin

Question 22

Carboniferous forests

Answer 22

360-300 Mya formation of Pangaea extensive lycopod forests
Changing atmosphere as CO2 levels dropped
led to rise of megaphylls (leafy plants)

Question 23

Horsetail innovations

Answer 23

Ring of xylem - better water transport + branching
Extensive roots (rhizomes) - better water uptake, vegetative spread, deciduous
Reproductive structures - strobili cone like structure produces spores

Question 24

Ferns (pteridophyta)

Answer 24

Have rhizomes + vascular tissues, megaphylls During reproduction, archegonium contains egg and antheridium encapsulates sperms

Question 25

Progymnosperms e.g Archaeopteris

Answer 25

reproduce by spores/gametophytes like ferns but has ring of vascular cambium - wood

Question 26

What caused fall of lycopods

Answer 26

Replaced by gymnosperms (naked seed) in the Permian due to new drying climate w/ Pangea formation opposed to warm wet tropical carboniferous

Question 27

How do cones and seeds work?

Answer 27

Cones - seed matures in female cone + pollen released from male cone, controlled seed release leads to embryo Seed- nucellus from mother feeds embryo + protected by seed coat

Question 28

Cycads

Answer 28

1st dominant gymnosperms, dioicous, drought tolerant, slow wood production

Question 29

Ginkgophyta

Answer 29

Dioecious, deciduous, fleshy seed wall, branching

Question 29

Pinophyta (conifers)

Answer 29

often monoecious, single extant order (pinales), long lived, grow fast + big, woody branched trees

Question 30

Gnetophyta

Answer 30

3 families v. different to one another, share feature w/ flowering plants

Question 31

Angiosperms

Answer 31

cased seeds protected by ovary, endosperm acts as storage tissue that feeds embryo, flowers innovated, capable of double fertilisation have xylem which are wider but prone to embolisms male + female organs found together

Question 32

Most primitive angiosperm

Answer 32

Amborella - has flowers but no vessels (only tracheids), dioecious, females have staminodes (infertile stamens)

Question 33

Evolution of fruit

Answer 33

resistant seeds tolerate gut environment so are spread + germinate w/ fertiliser, not exclusively angiosperm but mainly

Question 34

3 plants that have developed different methods to reach canopy?

Answer 34

Epiphytes, climbers, hemiparasites (root into stem of host + connect to xylem)

Question 35

Plants with short life span

Answer 35

Ruderals - weed species (short-lived) that exploit gaps in ecosystem/disturbance e.g. poppies Ephemerals - annual/perennial, grow following rain, persist as seeds or bulbs/roots

Question 36

Adaptation to manage low water in deserts

Answer 36

Biochemical convergence - CAM photosynthesis prevents water loss by closing stomata during day

Question 37

What are cotyledons?

Answer 37

'seed leaves' produced in embryo w/ different structure to actual leaves angiosperms - monocots, dicots

Question 38

Key fungi features

Answer 38

Hyphae - tubular filaments divided by septae into separate cells, cell walls contain chitin, growth from tips Mycelium - mass of hyphae, denser mycelium forms mushrooms, large SA:V increases absorption

Question 39

Saprotrophs

Answer 39

secreted enzymes decompose dead organic material

Question 40

Mutualism-parasitism continuum

Answer 40

Fungi are both: Mutualists - arbuscules exchange phosphate for assimilated carbon at root cell plasma membranes Parasites - hyphae grow into hosts + manipulate to yield more nutrients (biotrophs) or kill it and live off of remains (necrotrophs)