## QUESTION 1
The following table presents data obtained from an experiment to determine the number of pods produced per plant in an experiment in which nitrogen was added in varying concentrations. Each treatment was replicated ten (10) times.
| Replication | 0 | 5 | 10 | 20 | 40 |
|---|---|---|---|---|---|
| 1 | 8 | 7 | 9 | 10 | 9 |
| 2 | 4 | 8 | 8 | 9 | 7 |
| 3 | 6 | 7 | 9 | 9 | 7 |
| 4 | 7 | 9 | 8 | 10 | 8 |
| 5 | 6 | 8 | 7 | 11 | 7 |
| 6 | 5 | 7 | 9 | 12 | 8 |
| 7 | 8 | 6 | 8 | 9 | 6 |
| 8 | 9 | 7 | 9 | 7 | 6 |
| 9 | 5 | 8 | 9 | 9 | 7 |
| 10 | 5 | 8 | 9 | 8 | 8 |
**Use the data in the table above to answer questions i to vii:**
- i. What is the range of number of pods produced from each treatment (concentration of nitrogen)? *(6 marks)*
- ii. What is the arithmetic mean of the number of pods produced from each treatment? *(6 marks)*
- iii. Present the mean number of pods produced from the treatments on a bar chart. *(5 marks)*
- iv. What is the median number of pods produced by each treatment? *(11 marks)*
- v. What is the modal number of pods produced by each treatment? *(6 marks)*
- vi. Calculate the variance of the number of pods produced by the 10 mg/g treatment. *(5 marks)*
- vii. Calculate the standard error of the number of pods produced by the 10 mg/g treatment. *(4 marks)*
**Total: 43 marks (maximum 40 marks)**
---
## QUESTION 2
Answer the following questions by providing the most appropriate response in the blank spaces. Write your answers in the answer booklet. Spelling of single word answers and scientific terms must be correct to score.
- i. Seed-bearing vascular plants are referred to as ___________. *(2 marks)*
- ii. A plastid that stores starch is called ___________. *(2 marks)*
- iii. The arrangement of the calyx and corolla in the floral bud is known as ___________. *(2 marks)*
- iv. ___________ refers to the type of reproduction in algae in which the male and female gametes are morphologically different. *(2 marks)*
- v. The spores produced in basidiomycotina are called ___________. *(2 marks)*
- vi. Rod-shaped bacteria are called ___________. *(2 marks)*
- vii. The structure responsible for the absorption of water and nutrients in bryophytes is called ___________. *(2 marks)*
- viii. The extinct class of the pteridophyta is called ___________. *(2 marks)*
- ix. Organisms with membrane-bound organelles in their cells are referred to as ___________. *(2 marks)*
- x. The entire mass of hyphae in fungi is termed ___________. *(2 marks)*
---
## QUESTION 3
Give a brief explanation to the following concepts:
- i. Conservation of biodiversity *(5 marks)*
- ii. Ecological succession *(5 marks)*
- iii. Ecosystem *(5 marks)*
- iv. Food chain *(5 marks)*
---
## QUESTION 4
- a) In a tabular form, present the differences between the algae and bryophytes. *(10 marks)*
- b) Write short notes on the types and range forms of lichens. *(10 marks)*
---
## QUESTION 5
Discuss the different forms of root modifications in angiosperms. *(20 marks)*
---
## QUESTION 6
- a) Write explanatory notes on photosynthesis. *(10 marks)*
- b) Outline the general characteristics of the bryophyte. *(10 marks)*
---
---
# SOLUTIONS
---
## QUESTION 1 — Statistical Analysis of Pod Data
### Raw Data Summary
| Treatment (mg/g N) | Values |
|---|---|
| 0 | 8,4,6,7,6,5,8,9,5,5 |
| 5 | 7,8,7,9,8,7,6,7,8,8 |
| 10 | 9,8,9,8,7,9,8,9,9,9 |
| 20 | 10,9,9,10,11,12,9,7,9,8 |
| 40 | 9,7,7,8,7,8,6,6,7,8 |
---
### i. Range for Each Treatment
**Range = Maximum value − Minimum value**
| Treatment | Max | Min | Range |
|---|---|---|---|
| 0 mg/g | 9 | 4 | **5** |
| 5 mg/g | 9 | 6 | **3** |
| 10 mg/g | 9 | 7 | **2** |
| 20 mg/g | 12 | 7 | **5** |
| 40 mg/g | 9 | 6 | **3** |
---
### ii. Arithmetic Mean for Each Treatment
**Mean = Sum ÷ 10**
**Treatment 0:**
Sum = 8+4+6+7+6+5+8+9+5+5 = **63**
Mean = 63/10 = **6.3**
**Treatment 5:**
Sum = 7+8+7+9+8+7+6+7+8+8 = **75**
Mean = 75/10 = **7.5**
**Treatment 10:**
Sum = 9+8+9+8+7+9+8+9+9+9 = **85**
Mean = 85/10 = **8.5**
**Treatment 20:**
Sum = 10+9+9+10+11+12+9+7+9+8 = **94**
Mean = 94/10 = **9.4**
**Treatment 40:**
Sum = 9+7+7+8+7+8+6+6+7+8 = **73**
Mean = 73/10 = **7.3**
---
### iii. Bar Chart Description
A bar chart should be drawn with:
- **X-axis:** Nitrogen concentration (0, 5, 10, 20, 40 mg/g)
- **Y-axis:** Mean number of pods (scale 0–10)
- **Bar heights:** 6.3, 7.5, 8.5, 9.4, 7.3 respectively
- Bars should be equal width, properly labeled with a title: *"Mean Number of Pods Produced at Different Nitrogen Concentrations"*
---
### iv. Median for Each Treatment
(Arrange values in ascending order, median = average of 5th and 6th values)
**Treatment 0:** 4, 5, 5, 5, **6, 6**, 7, 8, 8, 9 → Median = (6+6)/2 = **6.0**
**Treatment 5:** 6, 7, 7, 7, **7, 8**, 8, 8, 8, 9 → Median = (7+8)/2 = **7.5**
**Treatment 10:** 7, 8, 8, 8, **9, 9**, 9, 9, 9, 9 → Median = (9+9)/2 = **9.0**
**Treatment 20:** 7, 8, 9, 9, **9, 9**, 9, 10, 10, 11, 12 → (9+9)/2 = **9.0**
**Treatment 40:** 6, 6, 7, 7, **7, 7**, 8, 8, 8, 9 → Median = (7+7)/2 = **7.0**
---
### v. Mode for Each Treatment
(Most frequently occurring value)
| Treatment | Values | Mode |
|---|---|---|
| 0 mg/g | 5 appears 3 times | **5** |
| 5 mg/g | 7 and 8 each appear 4 times | **7 and 8** (bimodal) |
| 10 mg/g | 9 appears 6 times | **9** |
| 20 mg/g | 9 appears 4 times | **9** |
| 40 mg/g | 7 appears 4 times | **7** |
---
### vi. Variance of the 10 mg/g Treatment
Data: 9, 8, 9, 8, 7, 9, 8, 9, 9, 9 — Mean = 8.5
| x | x − x̄ | (x − x̄)² |
|---|---|---|
| 9 | 0.5 | 0.25 |
| 8 | −0.5 | 0.25 |
| 9 | 0.5 | 0.25 |
| 8 | −0.5 | 0.25 |
| 7 | −1.5 | 2.25 |
| 9 | 0.5 | 0.25 |
| 8 | −0.5 | 0.25 |
| 9 | 0.5 | 0.25 |
| 9 | 0.5 | 0.25 |
| 9 | 0.5 | 0.25 |
**Σ(x − x̄)² = 4.50**
**Variance (s²) = Σ(x − x̄)² / (n−1) = 4.50 / 9 = 0.50**
---
### vii. Standard Error of the 10 mg/g Treatment
**SE = √(Variance/n) = √(0.50/10) = √0.05 = 0.2236 ≈ 0.22**
---
## QUESTION 2 — Fill in the Blanks
| # | Answer |
|---|---|
| i. | **Spermatophytes** (or Tracheophytes) |
| ii. | **Amyloplast** |
| iii. | **Aestivation** |
| iv. | **Anisogamy** |
| v. | **Basidiospores** |
| vi. | **Bacilli** |
| vii. | **Rhizoids** |
| viii. | **Psilopsida** (Psilophyta) |
| ix. | **Eukaryotes** |
| x. | **Mycelium** |
---
## QUESTION 3 — Concepts
### i. Conservation of Biodiversity
Conservation of biodiversity refers to the protection, preservation, and sustainable management of living organisms (plants, animals, microorganisms) and their habitats to prevent extinction and maintain ecosystem balance. It includes **in-situ conservation** (e.g., national parks, game reserves) and **ex-situ conservation** (e.g., botanical gardens, zoos, seed banks). The goal is to sustain genetic diversity, species diversity, and ecosystem diversity for present and future generations.
### ii. Ecological Succession
Ecological succession is the gradual, sequential, and directional change in the composition and structure of a biological community over time in a given area. It begins with **pioneer species** colonizing a bare environment (primary succession) or a disturbed area (secondary succession) and progresses through intermediate stages (seres) until a stable **climax community** is reached. Example: bare rock → lichens → mosses → grasses → shrubs → forest.
### iii. Ecosystem
An ecosystem is a functional unit of nature consisting of all living organisms (biotic components — plants, animals, decomposers) in an area interacting with each other and with their non-living (abiotic) environment (soil, water, air, sunlight, temperature). Energy flows through ecosystems via food chains and webs, while nutrients are cycled through biogeochemical cycles. Examples include forests, ponds, deserts, and coral reefs.
### iv. Food Chain
A food chain is a linear sequence showing the transfer of energy and nutrients from one organism to another through feeding relationships. It begins with a **producer** (green plant/autotroph) → **primary consumer** (herbivore) → **secondary consumer** (carnivore) → **tertiary consumer** → **decomposers**. Example: Grass → Grasshopper → Frog → Snake → Hawk. Energy decreases at each trophic level (about 90% lost as heat).
---
## QUESTION 4
### a) Differences Between Algae and Bryophytes
| Feature | Algae | Bryophytes |
|---|---|---|
| Habitat | Mostly aquatic | Mostly terrestrial/moist land |
| Body form | Thallus (no true organs) | Thallus or leafy (more complex) |
| Vascular tissue | Absent | Absent |
| Roots | Absent (rhizoids or holdfasts) | Absent (only rhizoids) |
| Reproductive structures | Simple (no protected embryo) | Archegonia and antheridia |
| Embryo | No embryo retained | Embryo retained on parent |
| Dominant generation | Gametophyte (mostly) | Gametophyte |
| Examples | Spirogyra, Chlamydomonas, Ulva | Mosses, liverworts, hornworts |
| Chlorophyll types | Varied (a, b, c, d) | Chlorophyll a and b only |
| Cell wall | Cellulose (some have other compounds) | Cellulose |
### b) Types and Range Forms of Lichens
Lichens are symbiotic organisms formed by the association of **fungi** (mycobiont) and **algae or cyanobacteria** (photobiont). The fungus provides shelter and absorbs water/minerals; the alga/cyanobacterium produces food through photosynthesis.
**Types of Lichens based on form:**
1. **Crustose lichens** — Form a thin, crust-like layer tightly attached to substrate (rocks, bark). They cannot be removed without destroying the substrate. E.g., *Lecanora*, *Rhizocarpon*.
2. **Foliose lichens** — Leaf-like, lobed, and loosely attached to the substrate. They have a distinct upper and lower surface. E.g., *Lobaria*, *Parmelia*.
3. **Fruticose lichens** — Shrub-like or beard-like, erect or pendulous, attached at one point. Most complex form. E.g., *Usnea* (old man's beard), *Cladonia*.
4. **Squamulose lichens** — Scale-like, intermediate between crustose and foliose; loosely attached with small overlapping scales.
**Range/Ecological roles of Lichens:**
- Pioneer organisms in primary succession (colonize bare rocks)
- Bioindicators of air quality (sensitive to SO₂ pollution)
- Found in extreme environments: arctic tundra, deserts, high mountains
- Used as food by animals (reindeer moss — *Cladonia*)
- Some used in dye production and medicine
---
## QUESTION 5 — Root Modifications in Angiosperms
Root modifications are structural adaptations of roots from their primary function (anchorage and absorption) to perform additional functions.
### 1. Storage Roots (Fleshy Roots)
Roots modified to store food (starch, water, or other nutrients.
- **Fusiform roots** — Spindle-shaped, tapering at both ends. E.g., Radish (*Raphanus sativus*)
- **Napiform roots** — Swollen at top, tapering abruptly below. E.g., Turnip (*Brassica rapa*)
- **Conical roots** — Broad at top, gradually tapering. E.g., Carrot (*Daucus carota*)
- **Tuberous roots** — Irregularly swollen, no definite shape. E.g., Sweet potato (*Ipomoea batatas*)
### 2. Prop Roots (Pillar Roots)
Arise from aerial branches and grow downward into the soil for additional mechanical support. E.g., Banyan tree (*Ficus benghalensis*), Maize.
### 3. Stilt Roots
Arise from the lower nodes of the stem, grow obliquely into the soil, providing support. E.g., Sugarcane, Pandanus, Maize.
### 4. Breathing Roots (Pneumatophores)
Found in mangrove plants growing in waterlogged/swampy soils. Roots grow upward out of the soil/water to absorb atmospheric oxygen through pores (lenticels/pneumathodes). E.g., *Rhizophora*, *Avicennia*.
### 5. Climbing Roots (Clinging/Adventitious Roots)
Used by climbing plants to attach to supports. E.g., Ivy (*Hedera*), Betel (*Piper betle*).
### 6. Assimilatory Roots (Photosynthetic Roots)
Roots contain chlorophyll and carry out photosynthesis. E.g., *Tinospora*, some orchids.
### 7. Haustorial Roots (Sucking Roots)
Found in parasitic plants; penetrate host tissue to absorb water and nutrients. E.g., *Cuscuta* (dodder), *Striga*.
### 8. Epiphytic Roots (Hygroscopic Roots)
Found in epiphytes; hang freely in air and absorb moisture from atmosphere using a spongy tissue called **velamen**. E.g., Orchids.
### 9. Contractile Roots
Shorten to pull the plant's organ (bulb/corm) deeper into the soil. E.g., *Allium* (onion), *Gladiolus*.
### 10. Nodular/Nitrogen-fixing Roots
Roots with nodules containing nitrogen-fixing bacteria (*Rhizobium*). E.g., Leguminosae family (beans, groundnuts, soybeans).
---
## QUESTION 6
### a) Photosynthesis
Photosynthesis is the process by which green plants, algae, and some bacteria use **light energy** (from the sun), **water** (from the soil), and **carbon dioxide** (from the air) to synthesize **glucose** (organic food) and release **oxygen** as a by-product.
**Overall equation:**
> 6CO₂ + 6H₂O + Light energy → C₆H₁₂O₆ + 6O₂
**It occurs in two main stages:**
**1. Light-dependent reactions (Light reactions):**
- Occur in the **thylakoid membranes** of the chloroplast
- Chlorophyll absorbs light energy (mainly red and blue wavelengths)
- Water molecules are split (**photolysis**): 2H₂O → 4H⁺ + 4e⁻ + O₂
- Oxygen is released as a by-product
- ATP and NADPH are produced
- Cyclic and non-cyclic photophosphorylation occur (Photosystems I and II)
**2. Light-independent reactions (Calvin Cycle / Dark reactions):**
- Occur in the **stroma** of the chloroplast
- CO₂ is fixed by the enzyme RuBisCO onto RuBP (ribulose bisphosphate)
- ATP and NADPH from light reactions are used to reduce 3-PGA to G3P
- G3P is used to synthesize glucose and regenerate RuBP
- Three turns of the cycle fix 3CO₂ and produce one G3P net
**Factors affecting photosynthesis:** Light intensity, CO₂ concentration, temperature, water availability, and chlorophyll content.
---
### b) General Characteristics of Bryophytes
1. **Non-vascular plants** — Lack true xylem and phloem; water and nutrients move by osmosis and diffusion.
2. **Habitat** — Found in moist, shaded, humid terrestrial environments; some are aquatic.
3. **Body form** — Simple thalloid body or differentiated into stem-like (cauloid), leaf-like (phylloid), and root-like (rhizoids) structures; no true roots, stems, or leaves.
4. **Rhizoids** — Unicellular or multicellular hair-like structures used for anchorage and absorption.
5. **Alternation of generations** — Dominant generation is the **gametophyte** (haploid, n); the sporophyte (diploid, 2n) is dependent on the gametophyte.
6. **Reproduction** — Both sexual (by gametes produced in antheridia and archegonia) and asexual (by fragmentation, gemmae, spores).
7. **Spores** — Haploid spores are produced in a **sporangium/capsule** on the sporophyte; dispersed by wind.
8. **Water dependency** — Require water for fertilization (motile biflagellate antherozoids swim to the egg).
9. **Size** — Generally small in size.
10. **Ecological role** — Pioneer organisms in succession; prevent soil erosion; retain moisture; provide habitat for invertebrates.
11. **Classification** — Three main classes: **Hepaticopsida** (liverworts), **Anthocerotopsida** (hornworts), **Bryopsida** (mosses).
12. **No seeds or flowers** — Reproduce by spores, not seeds.