Pests and diseases limit growth and development. Before planting, a farmer might treat the soil with pesticides and fungicides and remove weeds. Once the crop is planted, regular inspection is needed to detect the first signs of an infection or infestation so that treatment can be applied.
• Monocots are flowering plants which bear seeds containing one cotyledon; dicots are flowering plants with seeds containing two cotyledons.
• Monocots have fibrous roots, leaves with parallel veins and scattered vascular bundles in the stem.
• Dicots have tap roots, leaves with a network of veins and stems with cylindrically arranged vascular tissue.
• The seeds of flowering plants contain an embryo and a food store enclosed by a seed coat.
• Roots may be tap, fibrous, aerial or adventitious with central vascular tissue and a wide cortex.
• Stems may be herbaceous or woody.
• Leaves are flat, thin structures adapted for photosynthesis. They have an upper and a lower epidermis with stomata for exchange of gases.
• The main leaf tissue is the mesophyll; this is made of cells containing chloroplasts, which have chlorophyll.
• The vascular tissue in leaves is in the midrib and in the network of veins. It consists of xylem and phloem.
• Plants reproduce sexually, through pollination, and asexually by natural and artificial methods.
• Flowers consist of a flower stalk, receptacle, petals, sepals and the reproductive structures.
• The male reproductive structures are the stamens, which have a filament bearing anthers in which pollen grains (containing male gametes) are formed. • The female reproductive structures are the carpels, which consist of a stigma, a
style and an ovary in which the ovules (containing female gametes) develop. • Flowers may be self-pollinated or cross-pollinated by several pollinating agents. • Insect-pollinated flowers are brightly coloured, scented, with sticky pollen and
nectaries to attract insects.
• Wind-pollinated flowers are small, with no nectar and produce masses of light smooth pollen grains.
• Pollination and fertilisation are important to agriculture in the production of fruits and seeds in crop plants.
• Fertilisation is usually necessary for fruit and seed formation.
• Asexual reproduction may use vegetative organs, such as suckers and rhizomes; grafting and tissue culture are also used.
• Asexual reproduction produces genetically identical offspring without the formation or fusion of gametes.
Answers to !Ns
• Artificial methods of vegetative propagation result in identical plants that can be produced quickly in large numbers and are 'true to type'.
• Seed germination requires water, a suitable temperature and oxygen.
• Seed germination in dicots may be epigeal, when the cotyledons come above the ground, or hypogeal when the cotyledons remain below the ground. • Seedlings are raised in containers such as seedboxes, Speedling trays or plastic
bottles.
• Seeds need to be sown in a potting soil mixture (which provides nutrients), kept moist and at a suitable temperature. Seeds sown in containers are usually kept in a nursery.
• A seedbed needs preparation so that it is free from weeds and pests, will drain easily, is fertilised and the soil should have a fine tilth.
• Seeds may be sown by scattering, placing in drills, or mixing with sand or water. • If seedlings grow too closely they need to be thinned out to give them space. • Before transplanting to field plots, seedlings need to be hardened to get them
used to full sunlight.
• Plants respond to environmental factors such as light (phototropism) and daylength (photoperiodism).
1-101 One from corn, rice, sugar cane, bamboo for monocot or another correct
example; and one from cabbage, cotton , citrus for dicot or another correct example.
11112 Monocot flowers have parts in 3s, often petals and sepals are small
and inconspicuous. Dicot flowers have parts in 4s and 5s, with brightly coloured, large petals.
IT03 Tap, fibrous, adventitious and aerial.
ITN The xylem and the phloem are transporting tissues: xylem transports water and mineral ions, and the phloem transports food substances in solution.
ITQ5 The pericycle is a single layer of cells inside the endodermis. It produces
lateral roots and cambium tissue.
MN The epidermis has stomata; the cortex is narrower; there is no
endodermis; the vascular tissue is in strands or bundles and not in the centre; there is a central area of pith.
MR Herbaceous stems are soft and often green, whereas woody stems are hard and covered with a layer of bark.
ITQ8 Monocot leaves are long and thin with parallel veins and often with no
definite midrib; dicot leaves are broader with a network of veins and have a definite midrib.
ITQ9 Protects internal tissues; slows down the evaporation of water; stomata
allow gas exchange.
11-010 The seed coat, the micropyle and the scar (hilum).
11:111 Food is stored in the endosperm of a maize seed and in the swollen
cotyledons of a bean seed.
111112 The stamens consist of a filament which bears anthers in which the pollen
grains are formed.
ITC113 The function of the style is to connect the stigma to the ovary.
11:114 Pollination is the transfer of pollen from the anthers to the stigma.
111115 Three from: wind, water, insects, birds, humans.
1-1016 It is light and smooth so that it is easily carried in the wind.
Section B: Crop Production
11017 One male gamete fuses with the egg cell to form a zygote; the other male gamete fuses with nuclei in the ovule to form the food store.
11018 Any five from: bulb, corm, runner, rhizome, tuber, sucker, stolon. 11019 The propagation of plants by vegetative parts, not involving the
production (or fusion) of gametes. 11020 Sugar cane, cassava and sweet potato.
ITQ21 Tongue layering involves pegging down a stem to the ground where it will form roots; air layering involves making a cut, applying rooting hormone and keeping the region moist until roots form.
11022 The stock is the rooted stem; the scion is the piece of stem to be grafted on to the stock.
11023 Mango, avocado and sapodilla.
11024 Genetically identical plants; large numbers produced in a short time; can be disease-resistant; produce dwarf trees; quality can be assured; can propagate plants that do not produce viable seeds.
11025 When 100 seeds are planted, it is the number that germinate successfully.
6 ITQ26 Should be kept in sealed airtight containers and cool conditions. I ITQ27 Air (oxygen), suitable temperature and moisture.
1 11028 Because their seed coats are very thick and scarifying them allows water in more quickly.
11029 In epigeal germination, the hypocotyl elongates and brings the cotyledons above the soil. In hypogeal germination, the epicotyl elongates bringing the plumule above the soil but the cotyledons remain below the ground. 11030 Radicle emerges and grows down into the soil; the plumule covered by
the coleoptile emerges above the ground. The cotyledon remains below the ground and absorbs food from the endosperm.
11031 Any three from: seedboxes, Speedling trays, tin cans, plastic bags, plastic cups and plastic bottles.
11032 One seed planted in each compartment; no need for thinning out; easy and light to handle; easy for transplanting; can be used again.
11033 It is close to the field plot so that seedlings do not have to be transported. It saves the farmer time and labour.
11034 3 m long by 1 m wide; cambered for drainage; manured and fertilised; fine tilth.
11035 Scattered or broadcast; in seed drills; mixed with water; mixed with sand. 11036 Mixed with water in a watering can and sprayed on to the soil.
11037 It should be transparent to allow the light in for photosynthesis of the seedlings.
11038 Any two from: reduce competition for light; reduce competition for water; reduce competition for nutrients; provide more space for growth. 11039 To get them used to full sunlight.
11040 Early in the morning, late in the evening or when the weather is cloudy to reduce the effect of hot temperatures and avoid wilting.
11041 carbon dioxide + water -. sugar + oxygen In the presence of sunlight and chlorophyll.
11042 Light is needed for photosynthesis and the higher the light intensity the greater the rate of photosynthesis.
11043 carbohydrate + oxygen -, carbon dioxide + water + energy
11044 For the formation of new cells, for the maintenance of the protoplasm,, and for the transport of materials around the plant.
Examination-style
questions
11045 Plant cells lose their turgor and the plants wilt.
11046 Because the movement of substances against the concentration gradient requires energy from respiration.
11047 Some are absorbed by diffusion if there is a higher concentration in the soil solution than in the plant. If the concentration is greater in the plant than in the soil solution, ions are taken up by active transport.
11048 The xylem is specialised for the transport of water and mineral ions; the phloem is specialised for the transport of soluble food substances. 11049 Long-day plants grow vegetatively when the day length is short and
produce flowers when the day length is long. Short-day plants grow vegetatively when the day length is long and produce flowers when the day length is short.
11050 They grow long and thin, lack chlorophyll and have unexpanded leaves. They die eventually.
11051 Too much rainfall slows down plant growth; too little rainfall causes wilting and eventually death.
Multiple Choice Questions
1. Which of the following is NOT a characteristic of monocots? A seeds with one cotyledon
B long thin leaves with parallel veins C cambium present in stem and root D flower parts in 3s.
2. Which of the following plants is a dicot? A corn
B bamboo C sugarcane D cabbage
3. Which type of root system does a mango plant have? A tap
B fibrous C adventitious D aerial
4. Monocot leaves and dicot leaves both have: A parallel veins
B a definite midrib C palisade mesophyll D stomata
5. Which of the following is NOT a feature of insect-pollinated flowers? A long feathery stigmas
B brightly coloured petals C sticky pollen
D nectar 6. A stolon is:
A an underground shoot growing from the base of the plant B a swollen underground stem
C a slender creeping stem D a thick underground stem
7. Which of these plants has hypogeal germination? A kidney bean
B tomato C cabbage D pigeon pea
Vegetative organs
suckers
Two examplesbulbils
cormsrhizomes
Section B: Crop Production8. The process by which plants lose water in the form of water vapour is called:
A translocation B transpiration C photosynthesis
D absorption