Factors Influencing Growth (PDF)

2/4/2024 Topic 4 – Reproduction & Growth 4-4 Factors Influencing Growth Pg 228 to 243 How do environmental and genetic factors influence an organism's growth? What stimulates plant growth Which factors control plant and animal growth 1 Growth and Development of Organisms Factors influencing how orga...

2/4/2024 Topic 4 – Reproduction & Growth 4-4 Factors Influencing Growth Pg 228 to 243 How do environmental and genetic factors influence an organism's growth? What stimulates plant growth Which factors control plant and animal growth 1 Growth and Development of Organisms Factors influencing how organisms grow: Genetic characteristics from parents Access to resources e.g. sufficient good nutrition and rest in animals Conditions of the environment e.g. adequate sunlight for plants Response to stimuli e.g. growth in plants in response to gravity Plants and animals change over time, adapting to different stimuli for survival. 2 1 2/4/2024 Plant Responses and Growth Plant growth is controlled by responses to stimuli Hormones – chemical affecting growth and development of plant e.g. Auxin  speed up rate of plant cell growth and controls plant’s response to light. 3 Tropism in Plants Plant’s growth response toward or away from a stimulus. Stimuli that can trigger tropism  touch, gravity, light Thigmotropism: Plant’s response to touch Positive thigmotropism – grow towards touch e.g. in vines that grow towards object they touch to coil around it Video https://youtu.be/dTljaIVseTc 4 2 2/4/2024 Tropism in Plants Gravitropism: Plant’s growth response due to gravity Positive gravitropism – grow downwards towards Earth e.g. roots of plants grow downwards Negative gravitropism – grow upwards away from Earth e.g. shoots of plants grow upwards 5 Tropism in Plants Phototropism: Plant’s growth response to light Positive phototropism – grow towards light 6 3 2/4/2024 Seasonal Changes on Plants The amount of darkness experienced by plants affects the blooming of the plant. Photoperiodism: Plant’s response to the different length of day and night due to seasons. Some plants are affected and bloom only when the length of day and night is of a certain ratio. e.g. 7 8 4 2/4/2024 Seasonal Changes on Plants Dormancy: Period when organism’s growth or activity stops. Helps plant survive cold temperature and lack of liquid water. Signs of dormancy Leaves changes color to yellow, orange or red. Leaves stop making chlorophyll. Chlorophyll breaks down causing the yellow and orange pigments in the leaves to become visible. Sugar and water transported out of leaves for storage elsewhere. Leaves fall to the ground  ready for cold weather 9 10 5 2/4/2024 Environmental Conditions Plants need optimal supply of resources to grow to full potential. e.g. sufficient sunlight, water & nutrients. Lack of resources from the environment will hinder development of plant  unable to grow to full size or weaken its structure. Competition may limit the resources available for a plant. 11 Environmental Conditions Insects, worms and other pests can cause diseases that can affect plants as well. Citrus leaf curl can be caused by insect infestation, bacterial or fungal infection. 12 6 2/4/2024 Animal Growth Animal growth is also affected and controlled by internal and external stimuli. After fertilization, embryo may develop outside or within the mother’s body. 13 Animal Growth in an Egg – Outside Body e.g. invertebrates, fish, reptiles & birds Contents of the egg provide nutrients for the development of the embryo. Amniotic eggs  eggs covered with membranes and a leathery shell. Eggs of land vertebrates e.g. birds and reptiles. 14 7 2/4/2024 15 Embryo Development Inside Egg Embryo develop inside the egg that is kept within the parent’s body. Developing embryo gets nutrient from egg’s yolk. Egg may hatch before or after release from parent’s body. Eggs hatch after release from parent’s body e.g. crocodiles Eggs hatch before release from parent’s body e.g. sharks 16 8 2/4/2024 Embryo Development Inside Placental Mammals Embryo develops inside mother’s body Mother provides embryo with everything it needs during development Nutrients and gases are exchanged between the developing embryo and the mother through the placenta. Embryo develops inside its mother’s body until its body system can function on its own. Blood of the embryo does not mix with its mother. 17 18 9 2/4/2024 Life Cycles Many young animals (e.g. vertebrates) have young that look like adults from birth. Other animals undergo metamorphosis – major body changes as they grow and develop into adults. 19 External & Internal Factors Affecting Growth External factors  Environmental conditions that animal has little control over e.g. - Availability of food - Exposure to disease & parasites - Availability of space to allow animal to grow to full adult size 20 10 2/4/2024 External & Internal Factors Affecting Growth Internal factors  hormonal and genetic characteristics Genetic characteristics – Genes an offspring inherit from parents Hormonal characteristics – Hormones produced in the animals’ body. Some hormones e.g. testosterone, leads to generating of proteins which is important in muscle development and muscle strength. Males tend to produce more testosterone leading to larger build. 21 22 11 2/4/2024 23 24 12