plant reproduction

What is the function of reproduction?

Produce offspring that have identical copies of the parental genes

Generating new individuals that generically different

What is the annual plant growth cycle?

Annual: Completes its life cycle in 1 year

What are examples of annual life cycles?

Winter, autumn (seasons)

What is biennial life cycle?

Requires all or part of 2 year to complete its life cycle

What happens in biennial life cycle?

1st growing season - vegetative growth (plant photosynthesise, produce storage organs

Winter time - vegetative part is reduced

2nd season - produce flowers, seeds and die

What is perennial life cycle?

Plant live more than 2 years - produce vegetative growth (seeds, leaves, roots) and flowering for reproduction

What are herbaceous perennials?

Non woody, soft, die-back in winter

What are woody perennials?

Trees and shrubs, woody stems

What happens during alternations of generation?

Zygote (2n) → mitosis→ sporophyte (multicellular diploid -2n) → meiosis → haploid spores → mitosis → gametophyte → mitosis → gametes (n) → fertilisation → zygote

What is the specialised structure for sexual reproduction in angiosperms?

Flower

What is the dominant form in reproduction of angiosperms?

Sporophyte

What are examples of asexual reproduction?

Vegetative reproduction - fragmentation, budding, runners, apomixis (produce seed without fertilisation taking place)

What are the advantages of asexual reproduction?

In small numbers - don’t need pollinator or another plant

Fast, efficient = rapid pop growth, no need for pollinators, can quickly colonise areas

What are the disadvantages of asexual reproduction?

Physically unstable environment (sand dune, eroding landslide)

Unsuitable environment for seed germination and seedling establishment

Common in perennial plants (e.g. grasses and aquatic plants)

Eliminates genetic recombination, vulnerable to environmental changes (due to lack of diversity), limited adaptability

What are the advantages of sexual reproduction?

Produce genetic variation (increases diversity), adapt to changing conditions (survive and pass on traits), evolutionary advantage

What are disadvantages of sexual reproduction?

Slow, energy costly, requires 2 parents and successful pollination / fertilisation

What does meiosis provide?

Direct DNA repair mechanisms for oxidative damage in reproductive tissues

What 4 concentric groups do flowers contain?

Carpel, stamen, petal, sepals

What is the angiosperms life cycle?

Heterosporous (male and female spores)

Male gametophyte → pollen grains contain tube nucleus and generative cell

Female - female gametophyte contains egg and 2 polar nuclei

What happens in double fertilisation in angiosperms?

Double fertilisation - 1 sperm combines with egg → diploid zygote

1 sperm combines with 2 haploid nuclei → endosperm (3n)

How is self-fertilisation prevented?

Heterostyly, dioecious/monoecious, dichogamy, genetic self-incompatibility

Dichogamy

Stamen and ovule mature at different times (timing mismatch)

What are the two types of dichogamy?

Protandry and protogyny

Protandry

Male function precedes

Protogyny

Female function preceded male function

Heterostyly

Different floral morphs prevent same type pollination - having styles of different lengths relate to stamens in flowers

Genetic self-incompatibility

Genetic mechanism at the S-locus prevents pollen tube growth if alleles match - recognise and reject pollen from genetically related individuals

Dioecious

Either male or female flowers on different plants

Monoecious

Have both males and female flowers on the same plant

What are the 2 types of self-pollination?

Autogamy and gaitonogamy

Autogamy

Pollen moves to female part of the same flower

Gaitonogamy

Transfer of pollen between different flowers on the same plant

Cross pollination (allogamy)

Abiotic (wind, water), biotic (insects, birds, bats)