Colorado AgriScienceColorado AgriSciencePlant Science Plant Science

Colorado AgriScienceColorado AgriSciencePlant Science Plant Science

Unit 4: Plant Reproduction & GeneticsUnit 4: Plant Reproduction & Genetics

Lesson 2: Sexual Reproduction in Plants Lesson 2: Sexual Reproduction in Plants

Sexual Reproduction • Involves flowers, fruit, & seed• Sperm from male flower fuses

w/the ovum of the female plant• Results in recombination of DNA

– Results in genetically unique individual

– Allows plants to adapt & evolve to environmental change

Pollination • Transfer of pollen from the male to

the female part of the plant(s)• How pollination occurs

– Self-Pollination• Pollen from a plant pollinates a flower on

the same plant

– Cross-Pollination • Pollen from a plant pollinates a flower on a

different plant

Fertilization • Necessary in flowering plants in order for a

seed to develop • Double Fertilization

– Unique to plants– Two sperm nuclei involved in fertilization– 1st fertilization occurs when one sperm fuses with

the egg creating a zygote– 2nd fertilization occurs when the 2nd sperm

nucleolus fuses with the two nuclei in the embryo sac

• Results in the formation of the endosperm

Fertilization • Hybrid

– Fertilization occurring from parents that are genetically different

– Advantages • Best traits of each parent is expressed• Results in Hybrid Vigor

– Increased growth, drought resistance, or insect resistance is possible

Fertilization & Genetics • Genetic information is stored in

every cell of the plant in DNA• Segments of DNA, called genes,

establish the code for plant appearance and traits

• Genes are arranged into a set of chromosomes

Fertilization & Genetics • Diploid

– Normal sets of cells containing two chromosomes

• Haploid– Sex cells contain one chromosome

• When fertilization occurs, the single sets of chromosomes are combined into the double set, one from each parent

• Results in traits from each parent to be passed on to offspring.