Plant cycles (photosythn and Reprodcution)

Question 1

photosynthesis rxn and purpose?

Answer 1

6CO2 + 6H2O → C6H12O6 + 6O
- Convert light to energy for metabolism
- Present in all 3 domains of life - evolved more than once

Question 2

six events in the history of plant life?

Answer 2

1. Photosynthesis
   
   2. Photosynthetic eukaryotes
   3. Transition to land and air
   4. Vascular tissue
   5. Seeds
   6. Flowers

Question 3

Plant Transition to Land and Air:

Answer 3

• Nutrients must be obtained from soil
  
  • Expose to air threatens desiccation (drying out)
  • Newly fertilized zygotes are especially vulnerable
  • Land plants = embryophyte

Question 4

Land plants and Obtaining Nutrients:

Answer 4

• Must be obtained from soil
  
  • Symbioses with arbuscular mycorrhizae
  • Air could dry out green algae
  • Fungi grow into plant cells and supply nutrients
  • Plants provide sugar from photosynth.

Question 5

Haploid Life Cycle (Most Algae)

Answer 5

Only diploid cell = zygote

Process:
- Zygote undergoes meiosis immediately

• Haploid cells divide by mitosis → new individuals + growth

Question 6

Diploid Life Cycle (Animals, Some Algae)

Answer 6

Only haploid cells = gametes

Process:

Fertilization → zygote (diploid)
Mitosis → growth into adult

Question 7

Alternation of Generations (Some Green Algae)

Answer 7

Switches between diploid (sporophyte) & haploid (gametophyte)

🔹 Process:

Sporophyte (Diploid) → produces spores (asexual)

Gametophyte (Haploid) → produces gametes (sexual reproduction)

Question 8

Why are Zygotes (embryo) Vulnerable?

Answer 8

Embryo :
Early stages of growth following sexual reproduction

Embryophytes :
(land plants) –> evolved form embryo

Fertilization occurs within female gametophyte

Embryo Is nourished and protected by the female gametophyte
(Protection/feeding )

Question 9

Seed Germination

Answer 9

Needs proper conditions to grow

Hypocotyl → Initial stem growth

Cotyledon → Stores energy

Foliage Leaf (Epicotyl) → Develops into true leaves

Question 10

Double Fertilization

Answer 10

Unique to flowering plants!
1️⃣ Pollen tube grows towards ovule
2️⃣ Sperm travel through pollen tube:

1st sperm → Fertilizes central cell
2nd sperm → Fertilizes egg
🌱 Endosperm (3n) → Energy source for seed development

Question 11

Pollination

Answer 11

Pollen Transfer from Anther → Stigma

Carried by bees, wasps, flies, ants, butterflies, moths, birds, bats, etc.

🌼 Types:

Self-pollination → Same flower/plant

Cross-pollination → Different plants

Question 12

Female (Mega) Gametophyte Development

Answer 12

Inside the Ovule (2n):
1️⃣ Meiosis I
2️⃣ Meiosis II → 4 spores (1n)
3️⃣ Three nuclei degenerate (absorbed by surviving megaspore (1n))

Question 13

Male (Micro) Gamete Development

Answer 13

Pollen Formation
(in Anther, 2n):
1. Meiosis I
2. Meiosis II → 4 microspores (1n) (pollen grains) → Released from anther

3. Inside pollen grain:

Mitosis → Two cells form:
Larger vegetative cell
Smaller generative cell

4. Inside generative cell:

Mitosis → Two sperm (microgametes)

Question 14

Ovary & Ovules

Answer 14

Ovary → Becomes fruit
Ovules → Become seeds

Example: Jalapeño Pepper

Three carpels fused into a single ovary
Many ovules inside

Question 15

Heteromorphic Generations (Some Green Algae)

Answer 15

All life stages occur in water

Life Cycle:

Diploids (sporophytes) → Produce spores

Haploids (gametophytes) → Produce gametes for sexual reproduction

Question 16

Flowering Plant Life Cycle

Answer 16

Oogamy: Two different gametes

Megagamete (Egg, large, non-motile)

Microgamete (Sperm, small, motile)

Dominant Generation: Diploid (Sporophyte)
- Embryo develops into a seed
- Seed forms within the ovary (flower)
- Alternating generations

Question 17

Late Blight Disease Cycle

Answer 17

Cause:
Oomycete Phytophthora infestans

Spread:
- Zoospores swim in moist soil & water, moving plant to plant
Wind dispersal also occurs
Produces zoospores (motile spores)
- Once on a plant, they infect & grow through tissues

Reproduction: Mostly asexual
Sporangium Formation:

Question 18

What is Chuno?

Answer 18

“freeze-dried” potatoes:
- Traditional food in the Andes dating to at least the 1200s
- Potatoes freeze at night
- Thaw during the day, water is removed by walking on them

Question 19

Potato tubers

Answer 19

• Underground (or at ground level) starch storage structure growing from rhizomes (stems)
  
  • Potato eyes = buds
  • Can produce asexually through these tubers

Question 20

Denitrification, Nitrification, and Nitrogen fixing definition

Answer 20

Denitrification by bacteria converts nitrates (NO3−) to nitrogen gas (N2).

Nitrification by bacteria converts nitrates (NO3−) to nitrites (NO2−).

Nitrogen fixing bacteria convert nitrogen gas (N2) into organic compounds.

Question 21

Nitrogen Fixation Occurs in what bacteria?

Answer 21

• Cyanobacteria
  
  • Some soil bacteria
    ○ Free-living
    ○ Symbiotic