San Francisco de Paula, Science Department.
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      • Unit 1: Introduction to investigation >
        • How to write Lab Reports
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      • Unit 3: Classification of living things
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      • Unit 1 - What do scientists do? >
        • How to write a lab report
        • SI Units
      • Unit 2 - The Earth in the Universe
      • Unit 3: How can we study living things >
        • Unit 3a - Living things
        • Unit 3b - The Diversity of Life >
          • Monera
          • Protists
          • Fungi
          • The Plant Kingdom
          • The Animal Kingdom
      • Unit 4 - Ecosystems & Biodiversity
      • Unit 5: The systems of the Earth >
        • Unit 5a - The Geosphere and the Atmosphere
        • Unit 5b - The hydrosphere and the Biosphere
      • Unit 6: Our changing home >
        • Unit 6a: Internal Geodynamics
        • Unit 6b: External Geodynamics
    • Laboratory & Tasks
  • MYP Year 8
    • Yr8 Syllabus & Assessment
    • Contents >
      • Units 1, 2 and 3 - Measuring Matters >
        • Unit 1 Physical quantities and Scientific Activity >
          • Converting Units
        • Unit 2 Matter and its Properties
        • Unit 3 Pure Substances and Mixtures >
          • Concentration and units (g/L, % mass)
      • Units 4 and 5 - Chemical Cooking >
        • Models of the Atom
        • Electronic structure of matter.
        • Periodic table (distribution of elements).
        • Chemical formulation
        • Molecular mass
        • Moles
        • Types of reactions
        • Lavoisier's law: Balancing of equations
        • Reaction rates: Factors that affect the speed of a reaction
      • Units 6, 7 and 8 - Move It! >
        • Unit 6 - Motion (URM)
        • Unit 6 - Motion (UARM)
        • Unit 7 - Forces and Mass
        • Unit 8 - Energy and Transformations
    • Laboratory & Tasks >
      • How to write a lab report
  • MYP Year 9
    • Yr9 Syllabus & Assessment
    • Contents >
      • Unit 1 - General organization of the human body, health and illness >
        • Human cells: levels of organisation
        • Health and types of diseases
        • Preventing diseases
        • The Immune System
        • Transplants
        • Addictive substances and associated substances
        • Complete Unit 1
      • Unit 2 - Nutrition >
        • Nutrition and nutrients
        • The Mediterranean diet
        • The anatomy and physiology of the digestive system
        • The anatomy and physiology of the circulatory system >
          • Revision quizzes
        • The anatomy and physiology of the respiratory system
        • The anatomy and physiology of the excretory system
        • Nutrition Documentaries
      • Unit 3 - Interaction and Coordination >
        • The function and anatomy of the nervous system
        • The endocrine system
      • Unit 4 - The reproductive system >
        • Anatomy and physiology of the human reproductive system.
        • Gametogenesis
        • Menstrual cycle
        • Fertilization
        • Infertility, contraception and STDs
      • Unit 5 - Genetics >
        • DNA and genetic modification
        • Cells and Inheritance
        • MORE ON MITOSIS VS MEIOSIS
        • Mendelian genetics
      • Unit 6 - Evolution >
        • Evolutionary theories
        • Evolution Simulators
      • EXTRA Unit 7 - Ecology and the environment >
        • Ecology
    • Laboratory & Tasks
  • MYP Year 10
    • Yr10 Syllabus
    • Contents >
      • Unit 0 - Formulation
      • Unit 1 - Scientific Activity
      • Unit 2 - Kinetic theory
      • The Atmosphere
      • Unit 3 - Mixtures and pures substances: Colligative properties
      • Unit 4 - The structure of matter
      • Unit 5 - Stoichiometry
      • Unit 6 - Redox Reactions
      • Unit 7 - Movement
      • Unit 8 - Forces
      • Unit 9 - Electricity
      • Unit 10 - Energy
    • Revision
    • Assessments and Lab Sessionss >
      • Assessments >
        • Criterion D - Water crisis
      • Session 1 - Paper balls
      • Sessions 2 - Properties of substances
      • Session 3 - Preparing a Schlenk tube
      • Session 4 - Gas constant
      • Session 5 - Colligative properties
      • Session 6 - Job´s method
      • Session 7 - Redox titration
      • Session 8 - UARM
      • Session 9 - Hooke´s Law
    • PISA questions
  • DP Biology SL
    • Contents >
      • Topic 1: Cell biology >
        • 1.1 Introduction to cells
        • 1.2 Ultrastructure of cells
        • 1.3 Membrane structure
        • 1.4 Membrane transport
        • 1.5 The origin of cells
        • 1.6 Cell division
      • Topic 2: Molecular biology >
        • 2.1 Molecules to metabolism
        • 2.2 Water
        • 2.3 Carbohydrates and lipids
        • 2.4 Proteins
        • 2.5 Enzymes
        • 2.6 Structure of DNA and RNA
        • 2.7 DNA replication, transcription and translation
        • 2.8 Cell respiration
        • 2.9 Photosynthesis
      • Topic 3: Genetics >
        • 3.1 Genes
        • 3.2 Chromosomes
        • 3.3 Meiosis
        • 3.4 Inheritance
        • 3.5 Genetic modification and biotechnology
      • Topic 4: Ecology >
        • 4.1 Species, communities and ecosystems
        • 4.2 Energy flow
        • 4.3 Carbon cycling
        • 4.4 Climate change
      • C: Ecology and conservation >
        • C.1 Species and communities
        • C.2 Communities and ecosystems
        • C.3 Impacts of humans on ecosystems
        • C.4 Conservation of biodiversity
      • Topic 5: Evolution and biodiversity >
        • 5.1 Evidence for evolution
        • 5.2 Natural selection
        • 5.3 Classification of biodiversity
        • 5.4 Cladistics
      • Topic 6: Human physiology >
        • 6.1 Digestion and absorption
        • 6.2 The blood system
        • 6.3 Defence against infectious disease
        • 6.4 Gas exchange
        • 6.5 Neurons and synapses
        • 6.6 Hormones, homeostasis and reproduction
    • Labs >
      • Statistical analysis
    • Previous to 2015 >
      • Topic 1: Statistical analysis
      • Topic 2: Cells >
        • 2.1 Cell theory
        • 2.2 Prokaryotic cells
        • 2.3 Eukaryotic cells
        • 2.4 Membranes
        • 2.5 Cell division
      • Option F: Microbes and biotechnology >
        • F1 Diversity of microbes
        • F2 Microbes and the environment
        • F3 Microbes and biotechnology
        • F4 Microbes and food production
      • Topic 5: Ecology and evolution >
        • 5.1 Communities and ecosystems
        • 5.2 The greenhouse effect
        • 5.3 Populations
        • 5.4 Evolution
        • 5.5 Classification
      • Option D: Evolution >
        • D1 Origin of life on Earth
        • D2 Species and speciation
        • D3 Human evolution
      • Topic 3: The chemistry of life >
        • 3.1 Chemical elements and water
        • 3.2 Carbohydrates, lipids and proteins
        • 3.3 DNA structure
        • 3.4 DNA replication
        • 3.5 Transcription and translation
        • 3.6 Enzymes
        • 3.7 Cell respiration
        • 3.8 Photosynthesis
        • TO DELETE
      • Topic 4: Genetics >
        • 4.1 Chromosomes, genes, alleles and mutations
        • 4.2 Meiosis
        • 4.3 Theoretical genetics
        • 4.4 Genetic engineering and biotechnology
      • Topic 6: Human health and physiology >
        • 6.1 Digestion
        • 6.2 The transport system
        • 6.3 Defence against infectious disease
        • 6.4 Gas exchange
        • 6.5 Nerves, hormones and homeostasis
        • 6.6 Reproduction
    • Tasks >
      • Databases
    • Documents
    • DP Biology Resources
    • Interesting links
  • Biología 12º
    • Bloque 1. Bioquímica
    • Bloque 2. Biología celular
    • Bloque 3. Genética y evolución
    • Bloque 4. Microbiología y biotecnología
    • Bloque 5. Inmunología
  • IB Biología NS
  • IB Chemistry HL
    • Contents >
      • Year 1 >
        • Topic 0 - Formulation
        • Topic 1 - Stoichiometric relationships
        • Topic 2 and 12 - Atomic structure
        • Topic 3 and 13 - Periodicity
        • Topic 4 and 14 - Chemical structure and bonding
        • Topic 5 and 15 - Energetics
        • Topic 10 and 20 - Organic chemistry
      • Year 2 >
        • Topic 6 and 16 - Chemical kinetics
        • Topic 7 and 17 - Equilibrium
        • Topic 8 and 18 - Acids and bases
        • Topic 9 and 19 - Redox processes
        • Topic 11 and 21 - Measurement and data processing
        • Option D - Medicinal chemistry
    • Lab work >
      • SFP Campus lab reports
      • Internal assessment structure
      • Internal Assessment examples
    • Nature of science
    • General revision
    • Selectividad
    • General information
    • Extended Essay
  • Other resources for students
    • Science Fair
    • Science essays >
      • How to Reference
    • Chemical formulation
    • Laboratory >
      • How to write a lab report
      • Microscopy
      • Excel for graphs and calculations >
        • Calculate the mean and SD
        • Drawing graphs
        • Add error bars to excel graphs
      • Lab videos!
    • Further Reading >
      • Women In Science
      • Infographics
    • Proyecto integrado
  • Department Home page
    • The International Baccalaureate
    • Conceptual learning
    • How will I be assessed?
    • Primary Science Club
    • Science Activities Noticeboard
  • MYP Year 6
    • Yr 6 Syllabus & Assessment
    • Contents >
      • Unit 1: Introduction to investigation >
        • How to write Lab Reports
      • Unit 2: Living things
      • Unit 3: Classification of living things
      • Unit 4: Fungi, Protists and Bacteria
      • Unit 5: Nutrition I
    • Laboratory and Tasks
  • MYP Year 7
    • Yr 7 Syllabus & Assessment
    • Contents >
      • 7º PAI en español
      • Unit 1 - What do scientists do? >
        • How to write a lab report
        • SI Units
      • Unit 2 - The Earth in the Universe
      • Unit 3: How can we study living things >
        • Unit 3a - Living things
        • Unit 3b - The Diversity of Life >
          • Monera
          • Protists
          • Fungi
          • The Plant Kingdom
          • The Animal Kingdom
      • Unit 4 - Ecosystems & Biodiversity
      • Unit 5: The systems of the Earth >
        • Unit 5a - The Geosphere and the Atmosphere
        • Unit 5b - The hydrosphere and the Biosphere
      • Unit 6: Our changing home >
        • Unit 6a: Internal Geodynamics
        • Unit 6b: External Geodynamics
    • Laboratory & Tasks
  • MYP Year 8
    • Yr8 Syllabus & Assessment
    • Contents >
      • Units 1, 2 and 3 - Measuring Matters >
        • Unit 1 Physical quantities and Scientific Activity >
          • Converting Units
        • Unit 2 Matter and its Properties
        • Unit 3 Pure Substances and Mixtures >
          • Concentration and units (g/L, % mass)
      • Units 4 and 5 - Chemical Cooking >
        • Models of the Atom
        • Electronic structure of matter.
        • Periodic table (distribution of elements).
        • Chemical formulation
        • Molecular mass
        • Moles
        • Types of reactions
        • Lavoisier's law: Balancing of equations
        • Reaction rates: Factors that affect the speed of a reaction
      • Units 6, 7 and 8 - Move It! >
        • Unit 6 - Motion (URM)
        • Unit 6 - Motion (UARM)
        • Unit 7 - Forces and Mass
        • Unit 8 - Energy and Transformations
    • Laboratory & Tasks >
      • How to write a lab report
  • MYP Year 9
    • Yr9 Syllabus & Assessment
    • Contents >
      • Unit 1 - General organization of the human body, health and illness >
        • Human cells: levels of organisation
        • Health and types of diseases
        • Preventing diseases
        • The Immune System
        • Transplants
        • Addictive substances and associated substances
        • Complete Unit 1
      • Unit 2 - Nutrition >
        • Nutrition and nutrients
        • The Mediterranean diet
        • The anatomy and physiology of the digestive system
        • The anatomy and physiology of the circulatory system >
          • Revision quizzes
        • The anatomy and physiology of the respiratory system
        • The anatomy and physiology of the excretory system
        • Nutrition Documentaries
      • Unit 3 - Interaction and Coordination >
        • The function and anatomy of the nervous system
        • The endocrine system
      • Unit 4 - The reproductive system >
        • Anatomy and physiology of the human reproductive system.
        • Gametogenesis
        • Menstrual cycle
        • Fertilization
        • Infertility, contraception and STDs
      • Unit 5 - Genetics >
        • DNA and genetic modification
        • Cells and Inheritance
        • MORE ON MITOSIS VS MEIOSIS
        • Mendelian genetics
      • Unit 6 - Evolution >
        • Evolutionary theories
        • Evolution Simulators
      • EXTRA Unit 7 - Ecology and the environment >
        • Ecology
    • Laboratory & Tasks
  • MYP Year 10
    • Yr10 Syllabus
    • Contents >
      • Unit 0 - Formulation
      • Unit 1 - Scientific Activity
      • Unit 2 - Kinetic theory
      • The Atmosphere
      • Unit 3 - Mixtures and pures substances: Colligative properties
      • Unit 4 - The structure of matter
      • Unit 5 - Stoichiometry
      • Unit 6 - Redox Reactions
      • Unit 7 - Movement
      • Unit 8 - Forces
      • Unit 9 - Electricity
      • Unit 10 - Energy
    • Revision
    • Assessments and Lab Sessionss >
      • Assessments >
        • Criterion D - Water crisis
      • Session 1 - Paper balls
      • Sessions 2 - Properties of substances
      • Session 3 - Preparing a Schlenk tube
      • Session 4 - Gas constant
      • Session 5 - Colligative properties
      • Session 6 - Job´s method
      • Session 7 - Redox titration
      • Session 8 - UARM
      • Session 9 - Hooke´s Law
    • PISA questions
  • DP Biology SL
    • Contents >
      • Topic 1: Cell biology >
        • 1.1 Introduction to cells
        • 1.2 Ultrastructure of cells
        • 1.3 Membrane structure
        • 1.4 Membrane transport
        • 1.5 The origin of cells
        • 1.6 Cell division
      • Topic 2: Molecular biology >
        • 2.1 Molecules to metabolism
        • 2.2 Water
        • 2.3 Carbohydrates and lipids
        • 2.4 Proteins
        • 2.5 Enzymes
        • 2.6 Structure of DNA and RNA
        • 2.7 DNA replication, transcription and translation
        • 2.8 Cell respiration
        • 2.9 Photosynthesis
      • Topic 3: Genetics >
        • 3.1 Genes
        • 3.2 Chromosomes
        • 3.3 Meiosis
        • 3.4 Inheritance
        • 3.5 Genetic modification and biotechnology
      • Topic 4: Ecology >
        • 4.1 Species, communities and ecosystems
        • 4.2 Energy flow
        • 4.3 Carbon cycling
        • 4.4 Climate change
      • C: Ecology and conservation >
        • C.1 Species and communities
        • C.2 Communities and ecosystems
        • C.3 Impacts of humans on ecosystems
        • C.4 Conservation of biodiversity
      • Topic 5: Evolution and biodiversity >
        • 5.1 Evidence for evolution
        • 5.2 Natural selection
        • 5.3 Classification of biodiversity
        • 5.4 Cladistics
      • Topic 6: Human physiology >
        • 6.1 Digestion and absorption
        • 6.2 The blood system
        • 6.3 Defence against infectious disease
        • 6.4 Gas exchange
        • 6.5 Neurons and synapses
        • 6.6 Hormones, homeostasis and reproduction
    • Labs >
      • Statistical analysis
    • Previous to 2015 >
      • Topic 1: Statistical analysis
      • Topic 2: Cells >
        • 2.1 Cell theory
        • 2.2 Prokaryotic cells
        • 2.3 Eukaryotic cells
        • 2.4 Membranes
        • 2.5 Cell division
      • Option F: Microbes and biotechnology >
        • F1 Diversity of microbes
        • F2 Microbes and the environment
        • F3 Microbes and biotechnology
        • F4 Microbes and food production
      • Topic 5: Ecology and evolution >
        • 5.1 Communities and ecosystems
        • 5.2 The greenhouse effect
        • 5.3 Populations
        • 5.4 Evolution
        • 5.5 Classification
      • Option D: Evolution >
        • D1 Origin of life on Earth
        • D2 Species and speciation
        • D3 Human evolution
      • Topic 3: The chemistry of life >
        • 3.1 Chemical elements and water
        • 3.2 Carbohydrates, lipids and proteins
        • 3.3 DNA structure
        • 3.4 DNA replication
        • 3.5 Transcription and translation
        • 3.6 Enzymes
        • 3.7 Cell respiration
        • 3.8 Photosynthesis
        • TO DELETE
      • Topic 4: Genetics >
        • 4.1 Chromosomes, genes, alleles and mutations
        • 4.2 Meiosis
        • 4.3 Theoretical genetics
        • 4.4 Genetic engineering and biotechnology
      • Topic 6: Human health and physiology >
        • 6.1 Digestion
        • 6.2 The transport system
        • 6.3 Defence against infectious disease
        • 6.4 Gas exchange
        • 6.5 Nerves, hormones and homeostasis
        • 6.6 Reproduction
    • Tasks >
      • Databases
    • Documents
    • DP Biology Resources
    • Interesting links
  • Biología 12º
    • Bloque 1. Bioquímica
    • Bloque 2. Biología celular
    • Bloque 3. Genética y evolución
    • Bloque 4. Microbiología y biotecnología
    • Bloque 5. Inmunología
  • IB Biología NS
  • IB Chemistry HL
    • Contents >
      • Year 1 >
        • Topic 0 - Formulation
        • Topic 1 - Stoichiometric relationships
        • Topic 2 and 12 - Atomic structure
        • Topic 3 and 13 - Periodicity
        • Topic 4 and 14 - Chemical structure and bonding
        • Topic 5 and 15 - Energetics
        • Topic 10 and 20 - Organic chemistry
      • Year 2 >
        • Topic 6 and 16 - Chemical kinetics
        • Topic 7 and 17 - Equilibrium
        • Topic 8 and 18 - Acids and bases
        • Topic 9 and 19 - Redox processes
        • Topic 11 and 21 - Measurement and data processing
        • Option D - Medicinal chemistry
    • Lab work >
      • SFP Campus lab reports
      • Internal assessment structure
      • Internal Assessment examples
    • Nature of science
    • General revision
    • Selectividad
    • General information
    • Extended Essay
  • Other resources for students
    • Science Fair
    • Science essays >
      • How to Reference
    • Chemical formulation
    • Laboratory >
      • How to write a lab report
      • Microscopy
      • Excel for graphs and calculations >
        • Calculate the mean and SD
        • Drawing graphs
        • Add error bars to excel graphs
      • Lab videos!
    • Further Reading >
      • Women In Science
      • Infographics
    • Proyecto integrado
San Francisco de Paula, Science Department.
​Paragraph section header text

Kingdom Plantae

Key words

feature                         bryophytes                  herbaceous                       node   
to release                     pteridophytes              sporangium,                       leaf (leaves)
damp                           gymnosperms              vascular                            apix
cluster                          angiosperms                rhizome                           sepal
shrub                           tropism                        fronds                           calyx
to burst                        nastic                           sorus, -i                         corolla
petal                            stamen                         filament                       anther
carpel or pistal stigma      style                             ovary,-ies                      to fuse
ovule                           gamete                         zygote                         fleshy
ripe

1. What Is a Plant? ​

Plants or metaphytes are, autotrophic multicellular eukaryotes, with tissues.

​
  • Plants are multicellular, they are made of many cells.
  • They are eukaryotes; their cells have a defined nucleus in the cytoplasm.
  • They have tissues; their cells are specialised into tissues, organs (such as leaves, roots or flowers) and systems.
  • They are autotrophs; they make their own food by photosynthesis.
 
Besides these main characteristics, plants all have similar physical features that make them easily recognizable.

  • They have roots, stem and leaves, even though their shape may vary from one species to another.
  • They are green due to the presence of chlorophyll; a photosynthetic pigment.
They are non-motile. They are rooted to the ground. However, they do move when they open their flowers, fruits

​

Classification of Plants

Plants are classified into 4 groups: bryophytes or mosses, pteridophytes or ferns, gymnosperms and angiosperms.
Picture
2.1  Mosses and liverworts (Bryophytes)

Mosses and liverworts (Bryophytes) are the simplest plants. They are small, with no true vascular tissues, flowers nor fruits.


2.2  Ferns (Pteridophytes)

Ferns (Pteridophytes) are medium sized plants with true vascular tissues. They don’t have flowers nor fruits.

Picture
Picture
2.3  Gymnosperms 

Gymnosperms or conifers are plants with vascular tissues but without fruits.

They are trees or shrubs, mostly evergreen and they grow in different climates. However most of the species are found in colder climates and at higher altitudes than other trees. The features of a conifer are the following:
 
  • They have softwoods.
  • They have needle-like leaves covered by a very thick cuticle which prevents water loss.
  • The seeds are not enclosed in an ovary. Their seeds are ‘naked’, without protection from a fruit, in a cone.
 
Conifers reproduce sexually. The male cones of conifers produce pollen. The pollen is distributed by wind reaching the female cones. Once fertilization takes place, the female cone develops into a pine cone. The fertilized pine (female) cones grow seeds (pine seeds) which will eventually give rise to new plants.
 
​

Angiosperms

Angiosperms or flowering plants have vascular tissues, flowers and fruits.

Angiosperms are the most successful of plants. We can find an enormous variety of them, and they are the largest group. They have evolved into many species and adapted to all habitats
 
Flowering plants share the following general characteristics:

  • They have efficient, well developed vascular tissues.
  • They have broad leaves well adapted for photosynthesis.
  • They have bright colourful flowers.
  • Their seeds are enclosed in a fruit.
 
Flowering plants also reproduce sexually. The pollen is transported by insects or distributed by the wind from flower to flower. After a flower is fertilized, the fruit is formed in which the seeds are enclosed.
3.  More About Plants
 
3.1. Roots, stems and leaves

 
Roots: Subterranean organs. They anchor the plant, absorb water, mineral salts and other nutrients from the soil. They are also a reservoir for food.

The stem: Aerial organ. It keeps the plant upright, and the different organs together. It also transports substances throughout the plant.
 
Stems (shoots) can be herbaceous, if they are soft, or woody if they are hard. (The stem divides into branches where we can see nodes; small bumps from which other branches, leaves, flowers or fruits can develop. The space between nodes is known as internode. At the nodes and apix of the stems there are buds. From buds new leaves and branches are formed).

​Leaves: Laminated green organs where photosynthesis takes place and gas exchange occurs.


3.2. Photosynthesis and plant nutrition 

Plants are autotrophs. They manufacture their own food by the process of photosynthesis. They take inorganic compounds from the soil and the air, and with the energy from sunlight transform them into organic substances (sugars)

Picture
  • Plants take water and mineral salts from the soil through their roots. This mixture is called raw sap.
  • Raw sap is transported up the stem  to the leaves through vascular bundles
  • The leaves take carbon dioxide from the air, and through the process of photosynthesis, using the energy form sunlight, they transform the raw sap into elaborated sap. This elaborated sap contains nutrients (sugars = glucids).
  • The elaborated sap is transported to the rest of the plant also through vascular tissues, and to the roots for storage.

​

Photosynthesis: process by which plants elaborate organic substances from simple inorganic substances, like water, and carbon dioxide, using sunlight. The organic substances elaborated during this process are simple sugars like glucose. During the process of photosynthesis, oxygen (O2) is released as a waste product.
Picture





​The simple sugars manufactured during photosynthesis will be used by the cells to make other substances.

3.4  Respiration in plants
 
Plants, just like any other living organism, also respire. During respiration, the gas exchange is exactly the opposite as in photosynthesis. Oxygen is taken in and carbon dioxide is expelled as a waste product. Plants always respire.
 
Plants carry out photosynthesis and respiration during day time, and only respiration at night time.
​
​3.5  How plants interact and respond to their environment
 
Plants, like all living things, are sensitive to their environment. Since plants are non-motile, they respond to different stimuli by changing their growth patterns.
A positive response is when the plant moves towards the stimulus. And a negative response is when the plant moves away from the stimulus. Some of the responses to stimuli are temporary movements while others are definite changes.
Tropisms are permanent changes in a plant’s growth: ex. when a plant grows towards or away from light it is phototropism. A positive geotropism is when the root tries to find soil.
Nastics are temporary changes that have nothing to do with their growth; such as plants that follow the sun, or open (up) during the day and close at night.
Click here to play a respiration game and here to check your knowledge. 
​4.  Plants Reproduction 
            Plants can reproduce asexually or sexually.
 
            In asexual reproduction only one individual plant takes part. Asexual reproduction in plants is also known as vegetative propagation. Stem cuttings are a form of artificial propagation.
 
In sexual reproduction two sex cells of opposite sex (a female and a male sex cell) are involved. Inside the flower sex cells, called gametes, are produced. The male gametes are in the pollen of the flower, while the female gametes are in the ovary of the flower. After fertilization seeds develop, being able to grow into a new plant. 
The flower of an angiosperm (LINK TO ANIMATION)
            The flower is the reproductive organ system in angiosperms. The flower of an angiosperm is formed by the following parts:

  • The sepals are green leaf-like structures at the base of the flower which protect the flower before it opens. The collection of the sepals makes up the calyx.
  • The corolla, made up by the petals, protects the reproductive organs of the flower. The petals are brightly coloured leaves
  • The stamen is the male reproductive organ of the flower. It consists of an elongated filament with an anther at its tip. Each anther contains four pollen sacs filled with pollen grains. The male gametes are in the pollen grains.
Picture
  • The carpel or pistil (gynaecium) is the female reproductive organ of the flower. Its shape resembles that of a small bottle with an elongate neck and it is at the centre of the flower. The carpel consists of the stigma, the style and the ovary. The ovary contains the ovules, which contains the female gametes.
​
4.2. Pollination
 
In order for sexual reproduction to take place, the male gametes and the female gametes must meet. This is done by a process know as pollination.
Pollination is the transfer of pollen grains, containing the male sex cells (gametes), to the female flower parts, containing the female sex cells (gametes)
 
We can differentiate between self-pollination and cross-pollination. In self-pollination, the transfer of gametes takes place within the same flower. However, if the transfer takes place between two different flowers (from one flower to another) of the same species, we call it cross pollination.
 
Pollination is carried out by the wind or animals (usually insects but also some birds species such as hummingbirds) 

​
​4.3. Fertilization
 
Fertilization is the step that follows pollination. Once the grain of pollen has landed on the stigma of a flower, pollination is complete.
Now that the pollen grain is in the stigma of the flower, it grows a pollen tube that goes down the style. Eventually, the pollen tube will reach the ovary.
Once inside the ovary, the pollen tube opens up allowing the male sex cells move down and into the ovary where it will fuse with the female sex cell forming a zygote.
The zygote will turn into an embryo, which will be enclosed in a seed..

​

4.4 The formation of seed and fruit
 
After fertilization takes place, the flower undergoes a few changes.

  • The sepals and petals dry up and usually fall off.
  • The stamen, the stigma and the style also dry up (wither away), being left only the ovary, which grows and changes in colour. It has now become the fruit.
  • If the fruit contains lots of water such as an apple, a peach, a cherry, a grape etc., it is called a fleshy fruit.
  • However, if the fruit has little water and it becomes hardened such as peanuts, acorns, beans etc., it is called a dry fruit. ​
4.5 Germination of seeds
 
            When the fruit is ripe, it falls to the ground eventually releasing the seeds. Shortly after that, if the environmental conditions are good, the seed will germinate.
            The seed needs the following to germinate: a water supply, oxygen and a suitable temperature.
            During germination, the seed absorbs lots of water swelling up until bursting (splitting open) of the outer coat. Once the outer coat splits open the new plant begins to grow. 


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References:
Download Plantae notes HERE
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