Auxin and Seedling Growth Effects

This video tutorial from Three Sighs Lessons explores how light and gravity affect the growth of newly germinated seedlings, focusing on the role of the hormone auxin. It provides a detailed guide on conducting experiments to investigate these effects, including setting up control variables and analyzing results. The video also discusses phototropism and geotropism, explaining how seedlings respond to light and gravity. The tutorial is aimed at triple biology students and emphasizes the importance of understanding these required practicals.

What is the main focus of the experiment discussed in the video?

• Investigating the effect of soil type on seedling growth

• Investigating the effect of water on seedling growth

• Investigating the effect of light and gravity on seedling growth

• Investigating the effect of temperature on seedling growth

Which variable is considered the independent variable in the light intensity experiment?

• Light intensity

• Height of the seedlings

• Type of seed

• Volume of water

What is a control variable in the light intensity experiment?

• Growth direction

• Number of seedlings

• Light intensity

• Height of the seedlings

How often should the height of each seedling be measured during the experiment?

• Only at the end of the experiment

• Every other day

• Every day for at least five consecutive days

• Once a week

What is the role of auxin in phototropism?

• It has no effect on phototropism

• It inhibits growth on the side facing the light

• It accelerates growth on the side facing the light

• It concentrates on the side furthest from the light, causing faster growth

Why do seedlings in the dark grow the longest?

• They receive more nutrients

• They are trying to reach the light

• They have more energy stored

• They have more chlorophyll

What happens to the leaves of seedlings grown in the dark?

• They grow towards the light

• They remain small and yellow

• They become large and green

• They fall off

How does gravity affect the growth of roots in seedlings?

• Roots grow downwards towards gravity

• Roots grow sideways

• Roots grow upwards against gravity

• Roots do not respond to gravity

What effect does auxin have on root growth in response to gravity?

• It has no effect on root growth

• It accelerates growth on the upper side of the root

• It inhibits growth on the lower side of the root

• It causes roots to grow in random directions

What is the purpose of placing a dish of seedlings on its side in the dark?

• To test the effect of water availability

• To measure the effect of temperature

• To observe the effect of light on growth

• To investigate the effect of gravity on growth