Growth and Development Part 2 Learning Objectives • To learn about the shape of growth curves. • To learn about how animals and plants grow. • To learn about how to measure growth using different techniques. Success Criteria • I can interpret graphs and data on growth in animals and plants. • I can state the main difference between growth in animals and plants. • I can explain the advantages and disadvantages of measuring the dry and wet masses of organisms. Starter: Development The growth stages the girl went through in the video were: infancy childhood adolescence What other developmental stages will she go through in her life? Adulthood Are all developmental stages the same length? No. Adulthood is longest. During which one is growth rate quickest? Infancy. Old-Age What type of cell division results in growth? Mitosis. Growth • Unlike plants, animals only grow in the early stages of their lives. 220 200 male female Height (cm) 180 160 140 120 100 80 60 40 20 0 0 2 4 6 8 10 12 14 16 18 20 22 24 Age (years) • After the age of around 18-23, there is no more growth. • Cells only divide for repair after this time. Animal Growth • Animals grow to a maximum size and then stop. A humans maximum height is determined by genes and the environment. All parts of an animal grow and the whole body gets bigger. Onwards and Upwards (+ outwards) Answer question 8 in the new student textbook (pg. 34)… Make sure you read the axes carefully! The graph in this question is not the same type as seen earlier! Answers: 8a 14–16 8b Growth stops 8c Approx. 9–13 Plant Growth • Plants grow very differently from animals. • Plant’s don’t have a maximum size and can continue to grow. Cell division only takes place in special areas called meristems. Meristems are found at the tips of the shoots and roots. All other cells in a plant simply elongate rather than divide. Many plant cells retain the ability to differentiate, unlike animal cells Measuring Growth • The growth of both animals and plants can be measured by measuring increase in mass. • There are two ways to do this. Measuring: Wet Mass: This is the mass of the whole organism and can be measured when the organism is alive. Dry Mass: This is the mass of an organism with water removed. The organism must be dead. Use the graph below to answer Questions 9-11 in the textbook (pg. 35): ANSWERS: 9a - 2 9b - Lack of space, water or minerals 10 - To measure dry mass you need to kill the organism 11 - Growth is all over the human body but mainly in the meristems of the tree, tree continues to grow humans reach a finite size HIGHER GROWTH OF A BABY Complete Mini-Worksheet 3 • Use the purple section of page 35 to complete worksheet 3. ANSWERS: 1. Table should be filled in the same as on page 35. 2. The growth rate of the root tip is much greater because the root tip contains the meristem. This is where cell division occurs. The rest of the plant grows slower, because cells elongate rather than divide. EXTENSION: Answer questions 12-14. Measuring Growth • We grow very differently from plants because we only have two growth phases. • One just after birth and one during adolescence. All parts of a child grow quite evenly during childhood. However, this isn’t the case before birth, when the BRAIN grows much quick than any other body part… Baby’s Brain • In the womb, the head a of a baby grows faster than any other part. • The growth of the brain is a priority. • It has to grow quickly so that it can coordinate the rest of the human structure. Click to play video about foetal brain development PLENARY Plenary: Babies Using a white board or your book, draw the changes in the head and body size of a foetus as it grows. Your last drawing should be of the new born baby. Explain why the size of the head changes so much quicker than the body. Learning Objectives • To learn about the shape of growth curves. • To learn about how animals and plants grow. • To learn about how to measure growth using different techniques. Success Criteria • I can interpret graphs and data on growth in animals and plants. • I can state the main difference between growth in animals and plants. • I can explain the advantages and disadvantages of measuring the dry and wet masses of organisms.