Primary Productivity

Question 1

Light scattered, reflected and absorbed by clouds and atmosphere

Answer 1

45-50%

Question 2

Light reflected from surface ocean

Answer 2

4-5%

Question 3

Light absorbed by ocean (total surface radiation)

Answer 3

45-50%. ~50% infrared and ultraviolet- scattered and absorbed near surface. ~50% visible spectrum/ photosynthetically active radiation (PAR), decreasing with depth

Question 4

Photic zone

Answer 4

Well lit- photosynthesis can occur

Question 5

Dysphotic zone

Answer 5

Twilight, poorly-lit, no photosynthesis or growing plants

Question 6

Aphotic zone

Answer 6

No light, chemosynthesis only

Question 7

Nutrient concentrations

Answer 7

Highest in the deep ocean due to decay of otganic matter sinking through the water column

Question 8

Upwelling of nutrients

Answer 8

Nutrients are supplied to surface ocean biota by upwelling and vertical mixing of water masses. High primary production

Question 9

Areas highest in upwelling

Answer 9

Along the equator, continental margins and the Southern Ocean

Question 10

Density

Answer 10

A function of salinity and temperature

Question 11

Shallow stable mixed layer

Answer 11

Phytoplankton kept in a well-lit environment favourable for growth

Question 12

Deep mixed layer

Answer 12

phytoplankton mixed over greater depth range and range of light conditions –> less favourable for growth–> low growth rates –> low primary productivity

Question 13

Plankton

Answer 13

Derived from the Greek for ‘wandering’- they wander because they cannot control their motion against the current

Question 14

Phytoplankton

Answer 14

Single-celled plants, bacteria , protists. All photosynthesis. Dominant primary producers of the pelagic realm. Present througout the photic zone

Question 15

Importance of phytoplankton

Answer 15

Base of ocean food chains and food webs . Convert inorganic nutrients (C,N,P) into organic matter and provide food for consumers in higher trophic levels. Major O2 producers

Question 16

Pigments contained within chloroplasts

Answer 16

Chlorophyll a= dominant. Chlorophyll b, c, and d. Accessory pigments e.g. phycoerythrin

Question 17

Metabolism

Answer 17

All chemical reactions occurring in living organisms; allow organisms to grow and reproduce, maintain structures, respond to the environment

Question 18

Intermediary metabolism

Answer 18

Conversion of energy in food to energy available for cellular processes; conversion of food into building blocks for proteins, lipids, nucleic acids and some carbohydrates; elimination of metabolic wastes

Question 19

Respiration

Answer 19

A set of metabolic reactions that break down organic matter and release large amounts of energy- this energy supports other metabolic processes of all cells

Question 20

Vital processes carried out by cells needing energy

Answer 20

Cell division, movement, maintaining body temperature, building/synthesising molecules

Question 21

Food

Answer 21

The source of chemical energy for most living things; fats contain more than twice as much energy/gram as carbohydrates and proteins, which each contain similar amounts of energy

Question 22

Major groups of phytoplankton

Answer 22

Diatoms, Coccolithophores, Dinoflagellates

Question 23

Diatoms

Answer 23

Glass cell walls (“frustules”) formed by taking up dissolved silica from sea water. Two valves made of silica (SiO2) 20-200um in length

Question 24

Diatoms- key features

Answer 24

Inhabit all aquatic environments but dominant in high nutrient areas. Produce 20-50% of Earth’s oxygen/ year. Substantial contribution to total ocean OM. Large and widespread deposits on the ocean floor.

Question 25

Diatom taxonomy

Answer 25

Centric diatoms (order Centrales)= radially symmetric and dominate planktonic communities (appeared 120mya).
Pennate Diatoms( order Pennales)= Bilaterally symmetric. Typical of benthic, marine and freshwater communities (appeared 70mya)

Question 26

Organelles

Answer 26

Living parts or specialised substructures within the cell

Question 27

Plastids

Answer 27

Major organelles in plant and algal cells. Manufacture and storage of important chemical compounds. Often contain pigments used in photosynthesis

Question 28

Nucleus- diatom

Answer 28

At centre of diatom; often spherical or lenticular and encloses chromosomes and nucleoli

Question 29

Nucleolus

Answer 29

Composes of proteins and nucleic acids; transcribes ribosomal RNA (rRNA) and assembles it within the cell

Question 30

Protoplasm

Answer 30

All living parts within the frustule- cell membrane, nucleus, cytoplasm, mitochondria, plastids and other organelles

Question 31

Cytoplasm

Answer 31

Colourless gel-like plasma inside frustule and enclosed within cell membrane ~80% water- cytosol, hold all organelles (e.g. mitochondria) except the nucleus in eukaryotes

Question 32

Raphe

Answer 32

Elongated fissure in valves of pennate diatoms. Used by diatom for movement. Important for identification

Question 32

Diatom structure

Answer 32

2 interlocking valves:
- Epitheca: larger older valve with girdle elements (epicingulum)connected to it
- Hypotheca: smaller younger valve with girdle elements (hypocingulum)connected to it. Connective zone: overlapping girdle elements that connect the valves, sutures allow movement

Question 32

Septa

Answer 32

Partitions formed within valves- used to characterise diatoms

Question 33

Nucleoplasm

Answer 33

Holds the contents of the nucleus

Question 34

Diatom ornamentation

Answer 34

Valve surfaces are usually covered with striations, pores, spines, punctuations and/or raphes. Very important for diatom ornamentation

Question 35

Setae

Answer 35

Spine-like projections common in diatoms

Question 36

Increase cell surface area

Answer 36

Increases drag and reduces the cell’s sinking rate into deeper darker waters with less sunlight

Question 37

Asexual reproduction in diatoms

Answer 37

• Epitheca and hypotheca of parent cell both become epitheca of daughter cell; new hypotheca constructe
• Cell size limited by rigid cell wall* Each cell division creates smaller cells, so the average cell size of population decreases until cells are ~1/3 their maximum size
• When cells reach critical size limits, sexual reproduction and auxospore formation are triggered to restore population cell size