Year 10 Plants and transpiration - Biology

What substance makes up plant cell walls

Cellulose

Name the tissue that covers and protects the surface of plants

Epidermal tissue

Name the part of the plant that waterproofs the leaf surface

Waxy cuticle

Name the cells that contain lots of chloroplasts for photosynthesis

Palisade cells

Name the tissue in which gas exchange takes place in the leaf

Spongy mesophyll layer

How do gases move in and out of a plant

Carbon dioxide move in to the leaf through the stomata and oxygen diffuses out

What controls the opening and closing of stomata

Guard cells

Briefly describe the arrangement of xylem and phloem in the stem of a plant

Organised in vascular bundles, with xylem on the inside and phloem on the outside

State the function of xylem

Transports water and mineral ions from roots to other parts of the plant

State the function of phloem

Transports dissolved sugars and amino acids from leaves to the other parts of the plant

State the difference in structure between xylem and phloem

Xylem: Dead, hollow tube, no end walls, has lignin Phloem: Living, has end walls called sieve plates, no lignin

Name the process of the transport of dissolved sugars in plants

Translocation

Describe how a slide of cells can be produced for viewing with a light microscope

Place a drop of water on a slide. Slice a thin layer of tissue and mount on a slide using forceps. Add a stain using a pipette. Lower a coverslip with a needle.

What are the reactants for photosynthesis

Carbon dioxide and water

How do the reactants enter the plant

Carbon dioxide diffuses into the leaf via the stomata, water is absorbed from the soil through the roots by osmosis

Name the pigment in chloroplasts and its role in photosynthesis

Chlorophyll, absorbs light

How are palisade cells adapted for photosynthesis

Pack tightly together, near the surface of the leaf, contain lots of chloroplasts with chlorophyll to absorb light

How are spongy mesophyll tissue adapted in plants

Big air spaces and large surface area for efficient gas exchange and diffusion of gases

State an adaptation of the leaf for efficient photosynthesis

Broad leaves, thin, have chlorophyll, air spaces, guard cells regulate stomata opening

Describe the process of transpiration

Water evaporates through the air spaces in the leaf through stomata. Water is pulled up the xylem in the transpiration stream to replace water lost by the leaf and moves into the mesophyll layer by osmosis. The water then moves into the root hair cells by osmosis and then into the xylem cells in a continuous transpiration stream

What are the factors that affect transpiration

Wind/light intensity/humidity/temperature

How does temperature affect rate of transpiration

Higher temperature increases the rate

Explain why a higher temperature results in faster transpiration

More kinetic energy, particles move around more, evaporate easier

How does humidity affect the rate of transpiration

Higher humidity decreases rate

Explain why humidity affects the rate of transpiration

reduced concentration gradient between amount of water vapour in air and inside the leaf

How does wind or air flow affect the rate of transpiration

More wind increases rate as it maintains a steep concentration gradient

Name the equipment used to estimate transpiration rate

potometer

How can the bubble in the potometer be reset

By opening the tap and letting water in from the reservoir

Why is a narrow capillary tube used

increases the resolution (bubble moves further in a small time) so its easier to see small changes

How can humidity be increased around the shoot in a potometer

A plastic bag can be tied around the shoot

How do you calculate the volume of a cylinder

𝜋r²h

Why must the same plant be used in repeats

As they can have different sized leaves and therefore different transpiration rates and number of stomata

What is the purpose of the bung and Vaseline when setting up the potometer

To prevent the evaporation of water from anywhere other than the stomata