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Plant Reproduction
Reproductive Biology
| Question | Answer |
|---|---|
| Define asexual reproduction. | The production of new individuals from a single organisms without the fusion of gametes. |
| T or F. All offspring produced asexually are clones. | T |
| Give 4 examples of asexual reproduction. | 1) Binary fission in bacteria 2) Budding in yeast 3) Fragmentation in algae 4) Spore production in fungi |
| What is a spore? | A small reproductive structure produced by prokaryotes, protists, fungi and plants; composed of cytoplasm and one or several nuclei for dispersal and/or survival in unfavourable conditions. |
| What is tissue culture? | Growing plant or animal tissue in a sterile medium. |
| Define vegetative propagation. | Increasing the number of plants by artificially encouraging asexual reproduction. |
| Define vegetative reproduction. | Asexual reproduction in plants in which a fairly large part of the parent plant separates to become an independent individual. |
| List the 2 main types of plant hormone. | 1) Auxins 2) Cytokinins 3) Gibberellins |
| T or F. Auxins stimulate root growth and cytokinins stimulate shoot growth. | T |
| State two types of artificial propagation. | 1) Cuttings 2) Micropropagation (tissue culture) |
| Cuttings and grafting can be done to produce a plant which is comprised of cells with two different genotypes. What name is given to such organisms? | Chimeras |
| State 2 advantages of vegetative reproduction. | 1) New plants are easy to establish 2) Most plants are clones 3) Uniform appearance/reliable supply 4) Uniform size |
| State one disadvantage of vegetative reproduction. | Genetically uniform crops are at risk of the same pests and diseases for which they have no resistance. Greater risk of being wiped out. |
| Define totipotency. | A single cell's capacity to divide and generate all the differentiated cells within an organism. Examples of totipotent cells are spores, zygotes and plant cells. |
| What are meristematic cells? | Undifferentiated cells which are totipotent and capable mitotic division and growth in plants. |
| List 4 components which are required in plant tissue culture. | 1) Appropriate tissue 2) Suitable growth medium (sucrose and nutrients for energy) 3) Aseptic (sterile) conditions 4) Growth regulators (e.g. auxins and cytokinins) |
| List the 5 stages in plant tissue culture in sequence. | 1) Selection and sterilization of appropriate plant tissue 2) Explant placed in growth media 3) Multiplication (formation of callus) 4) Plantlets transferred to root media (hardening) 5) Plantlets transferred to soil |
| What are explants? | Tiny pieces of plant material cut from a parent plant. These may be pieces from the leaf, stem, root or bud. |
| Why is sterilization important tissue culture? | To kill any microbes( bacteria and fungi) present. |
| What is a callus? | A mass of undifferentiated, totipotent cells. |
| List 3 factors which can affect plant tissue culture. | 1) Plant species used 2) Age and health of donor plant 3) Nutrient medium |
| List 3 applications of plant tissue culture. | 1) Conservation of rare and endangered plant species. 2) Commercial production of plants used by florists. 3) To screen cells rather than plants for advantageous properties such as herbicidal resistance/tolerance. |
| List 3 advantages of plant tissue culture. | 1) Faster than seed growth 2) Disease-free clones with desirable characteristics 3) Plants that are infertile or hard to grow from seed can be reproduced |
| List 3 disadvantages of plant tissue culture. | 1) Expensive, labour-intensive 2) Process can fail due to microbial contamination 3) No genetic variation (except for mutations); cloned offspring susceptible to the same pest/diseases |
| Define self-pollination. | Transfer of pollen grains from anther to stigma within the same flower or between flowers on the same plant. |
| Define cross pollination. | Transfer of pollen grains from anther of one flower to a stigma in a flower on a separate plant. |
| List 5 agents of pollination. | 1) Wind 2) Insects 3) Birds 4) Water 5) Bats |
| List 5 characteristics of insect pollinated flowers which attract insect pollinators. | 1) Scent 2) Brightly coloured petals 3) Honey guides 4) Nectar 5) Pollen |
| T or F. Flowering plants have a variety of ways to promote cross-pollination and avoid self-pollination. | T |
| What is dioecy? | Method to promote pollination in flowering plants in which plants are either male or female, not hermaphrodite. |
| What is dichogamy? | Method to promote cross-pollination in flowering plants in which anthers and stigmas do not ripen at the same time ( protogyny and protandry) |
| Stigmas ripen before anthers in this method to promote cross-pollination . | Protogyny |
| Anthers ripen before stigmas in this method to promote cross-pollination. | Protandry |
| What is heterostyly? | Method to promote cross-pollination in which anthers and stigmas are at different heights in flowers. |
| What is self-incompatibility? | Method to promote cross-pollination in which pollen grains do not germinate and grow on stigmas of the same genotype. |
| What is male sterility? | Failure to produce pollen grains as a result of mutations. These plants cannot self-pollinate and therefore have to be cross pollinated. |
| This is term for breeding between individuals of identical, or very similar, genotypes. | Inbreeding |
| This breeding between different populations or varieties within a species. | Interbreeding |
| Step 1 of fertilization in flowering plants. | Pollen lands on the stigma of a compatible species and germinates. |
| Step 2 of of fertilization in flowering plants. | A pollen tube (from tube cell) emerges that starts to grow down the style to the ovary. |
| Step 3 of of fertilization in flowering plants. | As pollen tube grows, the generative nucleus divides by mitosis to produce two male gametes. |
| Step 4 of fertilization in flowering plants. | The pollen tube on reaching the ovule grows through the micropyle. |
| Step 5 of fertilization in flowering plants. | The tube nucleus degenerates and the tip of the tube bursts to release the male gametes. |
| Step 6 of fertilization in flowering plants. | Double fertilization occurs in which one male nucleus fuses with the female gamete to produce the zygote(diploid) while the other fuses with the polar nucleus to form the primary endosperm nucleus (triploid). |
| After fertilization, the zygote becomes | an embryo within the seed |
| After fertilization, the primary endosperm nucleus becomes | endosperm (nutritive tissue) within the seed |
| After fertilization, the integuments become | seed coat (testa) |
| After fertilization, the ovary becomes | fruit |
| State two important functions of fruits. | 1) Protect seeds during their maturation 2) Dispersion of mature seeds by wind, water, humans and animals. |
| Give one advantage of sexual reproduction in flowering plants. | Variation in offspring increases ability to withstand catastrophic changes in the environment. |
| Give one disadvantage of sexual reproduction in flowering plants. | Process takes a longer time than asexual reproduction. |
| Give 3 advantages of self-pollination. | 1) There is no waste of pollen grains 2) The purity of the species is maintained. 3) Faster process since the plants do not depend on pollinating agents. |
| Give 3 disadvantages of self-pollination. | 1)The seeds are less in numbers 2) Produced seeds are weak 3) Reduced resistance against diseases |
| Give 3 advantages of cross pollination. | 1) Production of new varieties 2) Seeds are produced in greater numbers and are more viable 3) Healthier plants produced with greater resistance to diseases. |
| Give 3 disadvantages of cross pollination. | 1) More waste of pollen grains 2) Unwanted characteristics may be introduced. 3) Pollinators are required and this is more time consuming. |
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CAPE Biology Unit 1
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